What if 2 People Have the Private Key?

[dejames]

What if 2 people have the private key. What happens then?

[achow101]

Both people can spend the Bitcoin associated with that private key. They can create transactions, but if they spend from the same outputs in their transaction, then only one person's transaction will actually confirm.

[Winner]

What if 2 people have the private key. What happens then?

If two people have the private key and they both have the wallet.dat file then they both could spend the coin without any issues.

[unholycactus]

What if 2 people have the private key. What happens then?

If two people have the private key and they both have the wallet.dat file then they both could spend the coin without any issues.

Just need the key.
You don't really own the coins that you have, you own the permission to spend them (the key).

[Kakmakr]

The Private key is the same as the password for your bank account. You can do whatever you want to do with the Private key, if you have access to it. This is why it is so important to safeguard that private key and why it is almost impossible to accidentally have someone generate the same Private key.

Do you want to share the private key with someone? or do you want to use {Multisig}  

[voise]

Sharing a private key is like sharing the combination of a safe, both people will be able to take out the valuable items in it.

[Mike Mayor]

What if 2 people have the private key. What happens then?

The public key you can share that is ok. The private one you shouldn't unless you trust that person with your wallet and the bitcoins contained within. It is a good idea to back up your private key in several places as well as keep a paper copy in your safe for example. A ledger would be best if you feel its worth the buy. Remember to keep your key safe. You sre in co trol of the safest and security of your own wallet. You are the bank !

[Wusolini]

Sharing a private key is like sharing the combination of a safe, both people will be able to take out the valuable items in it.

Exactly, by sharing your private key you also share the location of the safe (address) and the list of valuables inside ( anybody can check the BTC stored within address).
The other guy can just wait till there is more BTC stored before moving them.

-- DO NOT SHARE YOUR PRIVATE KEY EVER --

What if 2 people have the private key. What happens then?

The public key you can share that is ok. The private one you shouldn't unless you trust that person with your wallet and the bitcoins contained within. It is a good idea to back up your private key in several places as well as keep a paper copy in your safe for example. A ledger would be best if you feel its worth the buy. Remember to keep your key safe. You sre in co trol of the safest and security of your own wallet. You are the bank !

I don't think storing private key in several places is the best way ( more places stored  = higher chance somebody finds them ) so this is quite counterproductive.
Better to choose one or two really safe spots which you will be aware of after years  (there is lot of users who dig the private keys so deep they was not able to recover them = BTC lost)

also I would recommend to avoid marking the backup as bitcoin wallet or similar ( so the random finder can't be sure what this 'string' can be used for )

 

[Velkro]

Sharing a private key is like sharing the combination of a safe, both people will be able to take out the valuable items in it.

This describes it best visually also.
Tread carefully with your private key, keep it safe at all times.