the fur is flying

I'm sure this question has been asked at nauseum already, but here goes anyway!

I have 2 cats. The female is 3, and the male is 1 (same birthday, not related at all!! what are the chances!). The male is quite a character, and off goes off on kitty crazy modes. In the past, when the cats wrestled, it was always "fair", but now, they fight dirty and often. There's sometimes hissing, too. Is this a dominance issue? Both cats will initiate the wrestling matches, and neither of them seem desperate to get away from the other. Should I intervene, or let things get sorted out by themselves? (Elmo, the male, has long hair, and he loses clouds of hair with each match, but he has more fur to lose!)

By the way: both cats have all their claws.

I would use the vanilla extract tip and put some on each cat- under the chin, between the shoulders and at the base of their tail so they smell the same. Do this three times a day- if you are sure they are not sick in any way? Also if they are not neutered and spayed, I would get this done quickly as well. You can also use Feliway Comfort Zone Room Mister and run it continuously, it helps a lot!