On the DVD release of Once You Go Black 3, the main scene shows Mandingo cumming twice, including that HUGE first toss that Kayla's body yanks out of him just a few minutes in (he had to pull out a couple of times per minute to last that long). On the Behind the Scenes of that DVD, Mandingo has a third orgasm; it is definitely not a replay of one of the previous O's.
I like some of the funny theatre that takes place around this: Mandingo walking around the house after his first orgasm and before taking Kayla again, muttering and cursing Jules Jordan out, telling him that "I'm not fucking with you no more" because Jules keeps on matching him with actresses who are so hot that he can't hold his nut. Kayla starting to realize how turned on he is, even before the first orgasm, and teasing him- "Is my pussy too good for you or what?", "Is that pussy tight?", "You like your cock in my pussy?".
Mandingo is brought off a second time by Luci Thai in the Behind The Scenes on that same DVD. Odd editing decisions- I think it's a huge turn-on when the actor is both so potent and aroused that he cums multiples.