but never mind only, this is possible as experience.
always smiling.
Really feel sorry to hear that, But we also don't have any choice. we found two guys with same ETH address, Now we have to cancel their participation. If you have any proof that the second guy is fake, just ping me.
But im still not getting the point "What is his benefit of giving us your ETH address"
Dont know about this particular case but this can be easily escaped by making ether address or any address in future campaigns private data. So only you can see it, that way there is no way for somebody else to put the same address for any reason they might have.
Or even better sha1 it. That way we can check if address is correct and others cant see it.