What passages in the musical Les Miserables are actually the same tune?

For example, "empty chair and empty table" is actually the same as the aria of the bishop at the beginning; On myself is the same as Fantine's aria before she died, and so on. In fact, many musicals are written by theme, so many of them are the same, but the composer is very clever and has not been discovered by everyone. I think it will be very interesting if we sort it out, and it will be more helpful to discover the internal logic.