All my film SLRs are empty, but I have Velvia 50 in my Kodak Medalist, Provia 100F in my Electro 35, and I think Arista 400 in my Leica M2, plus 120 Portra 400 in my Yashica 635. That makes four.
Again, not sure if it counts, but it goes up to six because I have 3000B45 B&W Instant 4x5 film in my PA-45 holder, plus Kodak Portra 400 and Ilford HP5 4x5 in my standard holders. That makes six, since those film mags can go between my 4x5 monorail and my Super Graphic.
So, Six cameras loaded, 4 of them rangefinders.