The mystery is why Aztecs exists
Assuming it was in the same group that came back. It could've been returned from elsewhere. Ep4 came from Morroco as well.
Well, it's definite that Aztecs was included in the Sf-only sales package, whereas Marco, Reign and Crusade weren't. Trying to remember whether Romans was or wasn't - if it was, it would explain its survival, but not why it was also included (unless it's that, despite the separate production codes, it and Rescue were effectively produced as one six-parter with one production team. But that's a bit of a stretch given that Rescue was definitely sold without Romans in earlier packages)