Restoring a backup perfectly, what happens with my spend coins?

[JackH]

So I take a backup of my computer and I have some BitCoins in there. What will happen to it all if I restore the backup with the same data? Obviously there will be a bug, as the same money cannot exist two places at a time right?

Just curious to what is going to happen.

[matt.collier]

Are you restoring the backup onto the original system or onto a second system?  You do not want to run the bitcoin client from copies of the same wallet simultaneously.

[Pieter Wuille]

A wallet does not contain any coins - it cointains the private keys necessary to spend them. The information about the coins themselves is stored in the network.

If you use the same wallet in two places, the first to spend it, gets it.

[Frozenlock]

As matt.collier said, you don't want to use the same wallet at multiple location.

The reason is that Bitcoin will generate random new addresses when you make transactions. So even if you started with the same wallet, they will become different with time. You should really avoid that!