It is a simple fix, don't carry it as plus one. I fill up the magazine, chamber the 1st round and leave the magazine 1 short.
When the mag is maxed, it also puts more force on the slide from the top round, you will notice it is much more difficult to lock in a magazine with a full magazine and the slide closed than when you are one short. Guns are not meant to be carried with a full magazine, at least I do not think they are. A full magazine should be inserted with the slide locked back.
Now as for carrying your backup magazine, guess you have to live with the rattle.
I too have several different ones that rattle when full, can't remember which ones off the top of my head though. Was always a double stack that does it though.
Rosewood