May I add to this question? If there's two or more jam one can participate, can they submit a single game? Provided that the rules don't specifically restrict it and the game was made during the duration of the jam(s).
As long as the game was made during this jam's time frame, you are allowed to submit it here. I can't speak for other jams, but we allow and encourage to participate in multiple jams, so if the jams overlap and the game was made during the jam, then you can submit it here. Does that answer your question?