I agree -- that happens to me too, even on a single monitor. In my use case, it occurs when I give multiple searches to find photos, e.g. first by person, then by location, then by date. I can't remember whether I've added the photo to the collection yet or not, and the badge on the thumbnail doesn't help if the photo is already in another collection or you're in Loupe mode.
Though it's possible to reassign keyboard shortcuts in LR, in this case, I don't think that would help, since there's just a single underlying command that acts as a toggle.
You could file a feature request at the official Adobe feedback forum: Recently active topics in Photoshop Family about Photoshop Lightroom
Also, flagging the photo rather than adding it to the collection, and then adding all flagged photos to the collection, is a way to avoid the problem.
Thanks for that. I thought about flagging too but often I am flagging for other purposes as well and only want some photos to go into the target collection. Thanks for the link to the feedback forum as I have a few suggestions.