[Adam]

Originally Posted by Rob1968

Input form the table's probably the only way to know. Whenever near the table on a substitution, I make sure they're noting who's coming in the game.

A similar situation occurred in a game two weeks ago. B Coach was subbing for rebounding/defense and offense. B5 was replaced by B6, for rebounding on a free throw. The shot was successful. The horn sounded, and B6 headed off the floor, while A5 reentered, at the beckoning of my partner. I had to hit the whistle and tell the B Coach that A5 couldn't reenter, until the clock had started, and that A6 would have to remain until that time.
B Coach then asked, "Can I sub-in another player?" I said, "Of Course, Coach." And he brought another player from the bench, for A6.
My partner is in his first year of Varsity ball, and he said he hadn't thought of the "has to sit a tick" situation.

Had a coach try this on me once. The only reason I caught it is he did it with the player I had just called for the foul.