Okay so this is got me perplexed. On my weapon I have hip shooter I already had all three unlocked bronze silver and gold now then I went to another augment on that weapon didn’t like it so went back to hit shooter and pressed “augment weapon” without thinking and it put the bronze on it, it also used up the resources for the bronze. And then when I scrolled over to gold and hit augment it used up resources again so I used up over 500 weapons parts on augments I already own and I saw a help button earlier somewhere on this menu and it said that you did not have to pay weapons Parts if you already unlocked an augment.
And by looking at how many weapons Parts I do now have 760 when I started today with 1600 it’s done that several times when i switched between augments