I think I understand better. Your concern is not people having more than one key, but you want keys to display in All Keys by person (each listed under one person's name) instead of by key?
The GUI does not currently have a way of doing this, and I'm not sure it is feasible. For instance, keys having the same name in the user ID, may belong to different individuals with the same name; different User IDs on the same key may have different names (what name would the key be under); and any PGP user (including an attacker) can use whatever name in their User ID they wish. These are just off the top of my head, and might be able to be addressed.
However, you can request this as a Feature Request, and if you do, it will receive consideration.