In my humble opinion.. You can already carry two rifles, they should only add an option to swap them out without dropping one in the process.. and there is already a "debuff" implemented if you are carrying two rifles, you tend to run slower.. The option of having an additional rifle on the back should only be through extremely rare rifle holster or a bag.. that also prohibits your movement. or maybe a combination of Personal Defense Weapon (PDW, in a pistol slot maybe) and a sniper rifle should be allowed to have both holstered. and a 1 weapon limit for LMG's and other heavier weapons (50cal sniper..) as they get added.
