Originally Posted by lotus49
I agree with mikedt, it's probably not fake. However, you can check yourself. There is an app in the Play Store called Genuine Galaxy S4/S3/Note II that is free and well rated that will allow you to check whether your phone is genuine or not.
I would be very surprised if it is not genuine, but less surprised if someone has tampered with the IMEI after it was stolen.
Out of interest, which IMEI is the valid one?
All the knock-offs I've seen, sure there's never been any problem with mismatched/suspicious IMEIs and blacklisting. These all new cellphones straight from the factories.
The OP's problem shows one of the dangers of buying a used
phone from something like Craigslist. You have to be very careful and do your checks properly. Like meeting at a cellphone dealer who can verify to both parties that the phone is OK.