If it were me, I'd return it back to its original owner as long as he/she is able to provide a signed message with the address' private key proving the coin's ownership.
Thoughts?
![Huh](https://bitcointalk.org/Smileys/default/huh.gif)
Surely this is the most reasonable thing to do. We need to be nice to mankind. If a prove is provided or a honest contact is made if that is possible, then to return it is the right thing to follow
return 1 eth will be better than we should have problems later on, because 1 eth is not ours and we have to return. but it is impossible for someone to send to someone else's address by mistake, for that must be serious carelessness
Such mistakes are highly possible mate depending on the wallet involved.