Both studios are based in Orlando Florida, both produce adult but not pornographic content (well, MFF has some explicit stuff, but at least half of their content has people with all of their junk completely covered) so its only natural they exchange models.
Like, if you're a buff, straight guy, and are willing to put on tiny speedos and wrestle another guy in tiny speedos, and have that be on video, you're probably comfortable enough to have some closeup photos of your feet taken while you're topless.
There's a lot more shared models tho, going through the retired wrestlers list I recognize Sledge (MFF Manning), Rambo (MFF Brock), Mario (MFF Mario O), Jack McHawk, Hollywood (MFF Ethan), Edge (MFF Rocco), Brenden Cage, Tony (MFF Lex), Powerman (MFF Tad), Frank the Tank/Defeo, Tristan Baldwin, Monstro (MFF Randy), Beur (MFF Scott), Xavier, Michael Crowe, Devin (MFF Dev), Rocky Brick (MFF Donnie), Rex (MFF Jaxton), Eric Fury (MFF Sonny), Braden Charron, Brad Barnes, Batar (MFF Harley), Ace Hanson.
I'm sure I'm missing a ton of them.
Also, there's a few more studios in Florida that use the same models, most notably StraightFraternity, for which the owner of MFF, Rich did a few videos for. Also Rocco from TA did a shitton of stuff for CapturedGuys (which also shared a ton of models with MFF back in the day) and BukBuddies.