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I remember change addresses didn't exist on paper wallets and you could lose your funds in such an easy manner this way (having a paper wallet loaded with funds and not spending it all). I guess this still happens and there hasn't been any "fix" as a Bitcoin update for prevention, right? So OP, if you ever send your funds to a paper wallet, make sure you spend ALL of it when you import your paper wallet back in.
If you have 1BTC on paper, you import the paper privkey into a wallet and you only spend a part of it, the rest of the funds would go to another address (called a "change" address, as others above me said) which you won't have the access to. A private key only imports a single address, not a wallet. Or am I wrong?
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Yes, paper wallet is just one address for cold long-term storage. Most of the "modern" wallets (online/desktop/hardware) are now designed as HD wallets, so they generate many bitcoin addresses and change addresses based on one master private key (256bit number, i.e secret seed words). HD wallets use "change" addresses for inbuilt HD wallet addresses, but not for "imported" addresses by default. It is always recomended for unexperienced users to "transfer"/import the whole balance from paper wallet to HD wallet for subsequent transactions.
We do not no any other details how OP created the transaction: was it made manually? was it sent from paper wallet or HD wallet? was the addresses imported to some online exchange? etc.
As it has been already written above, all the outputs from address includes the inputs as well. The difference between inputs and outputs is the transaction fee (which is received by the mainer together with the bock reward). That's why, the
worst case for OP in this situation is that the transaction difference was considered as a transaction fee, and went to miner. In this situation OP could write the message to miner, explain the mistake and ask to return the funds.
By the way, "change" address could be also the same as the sending address. There are a lot transactions with the same change address, and the remaining difference returns to the initial address. But it is not recomended of course. The modern way is to use "own change" address which is generated within the same wallet.
Transaction scheme (1BTC = 0.3BTC + 0.699BTC + 0.001BTC):
[Sending address - 1BTC]
|
/ \
/ \-------------------------------------
/ \ |
[Receiving addr 0.3BTC] [Change addr 0.699BTC] + [Transaction fee 0.001BTC]
So,
if the transaction was made manually, and
the change address was not specified, so the remaining input (in the case above 1BTC - 0.3BTC = 0.7BTC) should be considered as the transaction fee, and went to miner's address together with the reward for calculated block (includes your transaction as well).
Hello! My transaction sent to two wallets, but I indicated only one wallet in sending,
Should I panic?
Share the transaction ID. If you do not want to share the transaction, just check if you have the access to the 2nd wallet. If yes - no panic. If no, and the transferred amount to that wallet significant for you - you can panic.