I actually found a new glitch. I'm not sure if this is new or not, but I'll post it anyway.
1.) First, make sure you have one human pistol out.
2.) Don't duel wield anything yet.
3.) Switch to your second weapon, (which has to be duel wieldable, like an SMG or plasma pistol.)
4.) Then duel wield that weapon (not your human pistol, but your other weapon)with something else.
5.) Now walk up to ANOTHER human pistol that is on the floor(not the one that you already have with you).
6.) While still duel wielding, pick up the second human pistol with "X", so that it becomes your primary weapon.
7.) Now drop your other duel wielded weapon with "Y". You should now have two human pistols in your inventory!
If you did this correctly, you will have a human pistol out. Press "Y" to switch weapons and your other human pistol will come up! What's is funny is to duel wield two pistols also, so in reality, you are sort of "triple wielding" weapons!