Could someone create a brand new Bitcoin address and find Bitcoin sitting in his wallet if someone accidentally sent coins to that address a year or so ago?
A while ago i asked my self the same question...
And yes, i agree with DannyHamilton's answers.
It is possible, but the chance that two people generate the same address and that someone has deposit coins on it is very very very small! It seems nearly not impossible...
And please think about the fact that you are able to also generate a address on a computer without internet connection. And you can send coins to this address without that this computer was connected to the internet ever.
This way i learned that a address is not bound to a user or to a wallet. And it means that there is not a mechanism which prevents that a address can generated more as to times.
The procedure of generating a address offline is good for some reasons, ( and the safest ) for example to generate a address and a private key to print it on a paper. Or for generating a unique address ( a vanity address). No hacker or bad software is able to find a offline generated address. And i am not able to calculate how long it could need to bruteforce a private key of a address with coins deposited on it. I think it is not possible during my lifetime, even if with computer which are 1000 times faster than today.