But in Shiwan Khan's case it's true.

Ok how about some rematches:
Green Lantern(hal) vs Silver surfer (not really a rematch though)
Aquaman vs namor
Thor vs Captain Marvel(Billy)

How about these:

Adam Warlock vs Captain Comet
Man Thing vs Swamp Thing
Kazar vs Cat Man
She Hulk vs Big Barda
The Fantastic Four vs the Doom Patrol (classic team)
Iron Man vs Steel
The Scarlet Witch vs Zatanna
Green Lantern vs Quasar
Namor vs Orion
The Vision vs The Red Tornado
Starlord vs Adam Strange

I actually was think about some of these match up when i was making this. (espically FF vs Doom patrol) Well here my two cents on some of these:
FF vs Doom Patrol: I have to go FF, Reed to smart to be stopped.
Iron Man vs Steel: Iron Man, Even though irons is very smart, Stark has better resources to make what he needs
The Vision vs Red Tornado: Red Tornado cus Red Tornado is the wind God Placed in a robot body.
Scarlet Witch vs Zatanna:Depends if we are talking about the Avengers Dissassemble Scarlet Witch who was rediculous powerful, then Zatanna would have a fight and in that case Scarlet Witch Would Win, by sayin "No More Zatanna" if not Zatanna all the way