At our chantey sing, the rule is not to repeat a song, and as there are only a finite number of well-known traditional chanteys, it often happens that somebody else sings the the song I weas going to do before I get to it. So I just sing something else. The trick is to know enough songs to be able to do that.
In one case, a newcomer who was just learning and knew very few songs as yet happened to glom on to most of my favorites. So I gritted my teeth and reminded myself that I knew many more songs and could afford to give a few up. That person has now passed on to other stuff that I don't sing.
In another case, I heard a song from an out-of-town performer at a festival, and decided to learn it. I knew I had heard it somewhere before but couldn't remember where, as the local guy who had sung it hadn't done it in several years (he did not write it). When I started singing it, it suddenly became his favorite song, and for about a year we would eye each other warily every month to see who got to it first. I didn't mind doing that, because he knows about a million more songs than I do. Finally we both got tired of it.