Don't look at me, over the last couple years I've submitted at least a half-dozen different tracks from the game at various intervals, in addition to whoever else would toss one in, and the only times anyone ever got them was when they were practically spoon-fed the answer (until a couple months ago, they got that one pretty quick).
What I do NOT do, and something that mildly irritates me about submissions, is I do not submit some obscure piece with some nebulous tune, or just some random background music. Those things could be to just about any game and you couldn't tell one from the other. I favor strong themes, preferably something that just sounds awesome. That's why I submit mostly 8-bit games; orchestration has made many themes less recognizable in recent years (I know the MGS theme code but would probably miss even the Halo theme if someone played it for me).