hello u thereI tried a few different glitches with a lvl 44 account and a prestige 3 lvl 20 one, i was trying to dupe a prestige 10 account over them and it didnt stick no matter what i did. I then tried it with a new account, a lvl 1 fresh from the barracks rookie mf and after playing a game and changing the clan tag the prestige saved. Then i made a fresh start on the prestige 3 account to see if it had to be lvl 1 to get the glitch to stick and i was right. In my case to dupe an account the dummy account MUST be at lvl 1. If your wondering what method just try anyone you like, i tried this with all the methods i know and it worked everytime.
Hope this helps!