I’m a frequent user of the multiple sources tags & I’d suggest they are (or should be) used as separate, but all related, sources. For example, if an old building in a similar location show up on three separate maps, or is described in 3 separate narratives, wouldn’t we want to know those references?
Oversourcing can certainly be a problem (one I’d love to have). But, under sourcing is a problem, as well. I believe the rule of thumb in academic research is to have at least 3 sources for any claim.