I recently bought a copy of Yes - 9012Live Yes: 9012 Live (1985) [VAL-3013]. I'm not overly concerned but the numbers on the cover and on the disc don't match and I was wondering if anyone else had it and could confirm one way or the other if my copy is a "marriage". My copy has a VAL-3013 cover (1985) but inside is a VAL-3813 disc (1986). It is quite conceivable that the later edition was issued in original covers (perhaps there was a great surplus of original covers?). I don't know this, and would like to know if anyone has any further information about it.
*EDIT* Of course, I have just up-dated the VAL-3013 submission with the mint marks from Yes: 9012 Live (1986) [VAL-3813] . In fact, on checking my submissions I hadn't done this. Just as well... *EDIT*

it could also be possible that someone had both and put the wrong disc inside the wrong sleeve.

Exactly. That is what I meant by the terms "marriage". If you've never met this term it is used in the antiques trade where elements from two eras are put together to make a complete object (like a C19th clock movement in a C18th clock case).