I have ruby throats too and they do not share; one usually tries to claim the feeder and sits in a nearby tree and keeps an eye on the thing, for a while, anyway. Hard to tell them apart, though you can notice behavior differences, so who knows how often the guard changes.
The Audubon people really need to look into name tags for birds so you can really tell them apart, and def know when the same bird manages to make it all the way back from migration.
