What happens when a transaction is found by more than one block?

[cryptothief]

Just did a quick bit of research and this is my 'non-technical' interpretation. The only way a transaction can be included in more than one block is if two miners reach it at the same time. Both would be broadcast and create a brief fork, with nodes building on whichever one they deem as correct (the first one they found) and rejecting the other one. It falls back into line once the next block is mined, confirming a winner and leaving the other initially legitimate block stranded. All subsequent blocks would then continue on the longest chain, with any nodes that found the stranded block first joining back in with the pack.

[FastCrypto]

That;s an interesting theory, I am not sure whether it is real in practice and what would need to happen so 2 miners would do action at the same time.