This is a weird one, I was thinking about it only the other week.
There have been countless times for me when somebody has requested a track and I have replied “sorry I’ve already played it’ (even sometimes when I haven’t) and the requester has just accepted that. But really, who cares if you have already played it? Particularly in a place with high traffic, like a bar or ‘unconventional’ spot, like clothes shop or convention/car show.
If you sense a perfect time for a track, you know its going to work don’t let the fact that you played it at the beginning of the night, possibly to a different set of people, stop you from throwing on that jam!
as part of a set, you could see the parts of the track as a reoccurring motif, and part of the theme you have created.
cheers
jp