Duplicated transactions

[Plumey]

G'day, I'm an old fart who's been collecting bitcoin since early 2017. I've got a rough idea how it all works but I still freak out when I have to do transactions so I would appreciate some advice on a strange situation.
Back in September I did a small sample transaction from an exchange to my Ledger Nano S - worked perfectly so I went ahead to transfer the full exchange BTC balance to the Ledger as well.
The transaction status came back cancelled so I just left the balance in the exchange because I couldn't work out what happened?
Today I decided to do the transaction again and this time it worked with no problems.
When I went into the Ledger to make sure it was received I noticed that the exact same amount was also there for the previous transaction..... so it went through twice.
To me it seems like the exchange screwed up somehow but how can that be given the foolproof nature of the blockchain??
Can anybody set me straight on how this shit happens?

[1713925804]

1713925804

[1713925804]

1713925804

[1713925804]

1713925804

[1713925804]

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[ranochigo]

Bitcoin does not prevent repeated transactions that are sent by accident. Bitcoin's Blockchain only prevents funds from being spent twice, in two separate transactions and both being included in the blockchain. It does nothing if the exchange accidentally sends you the funds twice, that'll be a technical error on the exchange's side.

For both of the transactions, do they both have confirmations and are they visible on the blockexplorers when you search your address? Which exchange are you using?

[LoyceV]

The transaction status came back cancelled so I just left the balance in the exchange because I couldn't work out what happened?
Today I decided to do the transaction again and this time it worked with no problems.
When I went into the Ledger to make sure it was received I noticed that the exact same amount was also there for the previous transaction..... so it went through twice.
To me it seems like the exchange screwed up somehow but how can that be given the foolproof nature of the blockchain??

Which exchange did you use?

There are 2 possibilities:
1. The exchange screwed themselves big time and didn't reduce your balance after your withdrawal in 2017.
2. Your 2017 transaction didn't confirm or maybe was double spent back in 2017, and your Ledger app isn't properly synchronized.

To check: if you search your receiving address on Blockchair you can check which scenario really happened. If you used a different address now than in 2020 you'll have to search for both of them on Blockchair.

Welcome to Bitcointalk. If you receive any PMs offering to "help" you, it's safe to assume they're trying to scam you.

[Pmalek]

Are you sure that the duplicate transaction you see in your Ledger Live (assuming you use Ledger Live) isn't just from the first test transaction you performed? How many incoming transactions are there in total, 2 or 3? Is your total sum of bitcoin now bigger than what you initially had or is it the same?

The way exchanges work is that they pool the coins together in a pool and when you request withdrawals, they fish out random coins and send them to you. Let's say this pool has 1000 bitcoin. You make a 1 bitcoin withdrawal and the exchange will send 1 bitcoin to you from its total stash. If the withdrawal went through, your account should no longer indicate that you still have coins in your balance. There might have been a bug or a human error on their end where they didn't save and update the correct balance of your account. It's a very unusual case though.

[Plumey]

Looks like I might have scored a Christmas present???
Both transactions confirmed on my Ledger.
How do I show screenshots on here?
(prefer not to mention the exchange)

[Pmalek]

You can upload a screenshot on https://imgur.com/ and share the link here. Just make sure the image doesn't contain any identifiable information about you, your whereabouts, or your bitcoin balance and addresses. It's in your own interest to protect your privacy and stay anonymous.

Merry Christmas I guess  

[LoyceV]

(prefer not to mention the exchange)

If you're planning on keeping this a secret you shouldn't post any addresses.
And if you did KYC on the exchange, they might come for the funds later. Depending on your location that may or may not become a problem.

[AB de Royse777]

And if you did KYC on the exchange, they might come for the funds later. Depending on your location that may or may not become a problem.

I think it will depend on the amount. If it's an amount such like $10/$100 maybe they won't bother but if this is a large amount then they will come after OP for sure. Mind that even if they have not done the KYC, the exchange should have his IP location unless he uses any VPN - they can easily find a way.

@Plumey, my suggestion will be to contact the exchange and give the fund back. That's not your money of course.

[Plumey]

Thanks for the informed feedback and help to explain.
Transactions both happened and confirmed - 0.03290264 BTC x 2 in my hardware wallet.
Not very often the small guy gets a win from the big end of town.
I think I'll cancel my account with the exchange and see what happens.
This could be the gift that keeps on giving as the BTC price increases

 
   















   


 
   















   

[LoyceV]

Transactions both happened and confirmed - 0.03290264 BTC x 2 in my hardware wallet.

Now you've just given away your Bitcoin address.

I won't post it here, but judging by the transaction history (without batched transactions) it's not a large exchange.

I think I'll cancel my account with the exchange and see what happens.

I don't think that matters, they'll still keep records.

Have you considered it might be worth a bug bounty to the exchange?

[AB de Royse777]

Transactions both happened and confirmed - 0.03290264 BTC x 2 in my hardware wallet.

It's only $811.20. If you think that worth to take the risk then good luck to you. There are instances where I have seen people to scam others 1000 times higher than this amounts (hackers). I personally even lost over 0.5 BTC in this forum and I believe I am just having fake promises and will not get this BTC back anytime LOL.

[Plumey]

Just to clarify.....if at some point in the future they persue the transaction then I will return the $342 for the original transaction that they screwed up - cash not BTC.
Tough one - if I screw up a transaction then my BTC are lost forever. Exchanges have plenty of disclaimers explaining this - does it work both ways?
If you have my bitcoin address please make a deposit to confirm  

[LoyceV]

If you have my bitcoin address please make a deposit to confirm  

Lol. How about I tell you the last character is an E.

[AB de Royse777]

Just to clarify.....if at some point in the future they persue the transaction then I will return the $342 for the original transaction that they screwed up - cash not BTC.

Imagine BTC price is under $1k at that time :-P
So, for $342 you will need to pay 0.342 BTC LOL

Anyway, it does not matter what you write or promise here. This is just a forum. They have their terms and conditions. If they take it to the law then the law will decide what to do.

[Plumey]

LoyceV - yes one of the addresses does end in an E - is that a bad thing?
I'm just an old fart so Tech takes me a bit to get my head around but I'm always learning.
If you want to make a deposit I'll give you another address just in case I can't access that one anymore?? 

Royse777 - if BTC tanks that much mine will be well and truly sold beforehand.
I think it's more a principle that anything - yes the exchanges do have their terms and conditions and they make sure they tell you that if you make a mistake your coins can be gone forever.
I deposited my funds to their exchange, I purchased BTC and paid a fee to do so, they clipped me on the USD rate and when I tried to transfer my BTC to another wallet they screwed up the transaction.
The same should apply to them. If they find their error and chase me for the funds then I will return the $342 from the original transaction that they stuffed up.
I doubt they will try to get the regulators involved.

Yes, this is just a forum but I appreciate the input from you blokes in explaining the processes to me - Thanks a lot!!

[o_e_l_e_o]

is that a bad thing?

Depends on how private you are trying to be. By revealing the date and amount of your transactions, it is trivial to find the two addresses in question and now link them together as both belonging to you.

I doubt they will try to get the regulators involved.

Well, it depends. Given you say that you deposited fiat to the exchange in order to buy BTC, then presumably the exchange knows at a minimum your name, email address, and bank details, and potentially also your physical address, phone number, and anything else you told them or was on any documents you uploaded when undergoing KYC. If they realize their mistake they will want 0.0329 BTC back, not $342. If you don't pay, then they simply pass your details to a debt collector. It won't take much effort on their part. Yes, it was their mistake, but that doesn't mean you are any less liable.

[Pmalek]

I agree with Royse777 here. The money isn't yours. If it's a small exchange who manually verifies and sends out withdrawals, someone somewhere might have been forced to pay the difference out of his own pocket for messing up. Or even worse, lost his job for his carelessness.

I was on the receiving end of money that didn't belong to me a few years ago in a signature campaign. Instead of receiving 0.015 BTC, some staff member of the casino deposited 0.15 BTC into my account. Over $1000 worth of bitcoin at the time. I could have kept my mouth shut and sent the money to a wallet but I gave it back. Actually I made them aware of the mistake and they took it back, but it's the same thing.

I am not a religious guy or anything like that, but you often hear people speaking of karma. A few weeks after that incident with the wrongly deposited BTC, I purchased a scratch card while waiting on someone. I won around $750 in my local currency just like that. Karma I guess.

[HCP]

Seriously tho... I had an issue on an exchange once, they "over credited" my account after I used RBF to increase the fee on a deposit transaction and the exchange credited BOTH transactions... they eventually figured it out and debited the BTC amount after I had already (mistakingly) used the funds for trading, which put my BTC balance into negatives Thankfully the price had dropped by then, so I was able to "re-buy" the BTC to put my account back to 0 and still make a tidy profit

The moral of the story is that they'll most likely figure out their mistake sooner or later...