I have seen emails with two "Return-Path" headers before. A case where that might occur could be if the email was accepted at a POP email address, and then later the owner of the POP email address that originally received the email then forwarded it on to another address. There might already be one Return-path header as a result of the first receipt, and then forwarding it could cause another one to be added, depending on how the mail systems involved handle the email.
However, the example you show just looks plain bogus to me. I guess the spammers are up to new tricks.