General Rules, Weapon Parts?

I am trying to go through my inventory and get rid of stuff that is out of whack and modded compared to what the game can legitimately drop. The last two weeks have been pretty hectic and I have had stuff sent to me by a ton of guys and am sure I have some modded gear in my inventory that I want to ditch.

For instance, I have an excellent OPQ that was sent to me but when I look at the overall parts list, it has two Grips and two Foregrips. The parts look like they fit on top of each other just fine…not stick out, but I have no clue.

Is there a general rule of how weapons can spawn in BL3?

How many Barrel or Body Accessories can a weapon have? Only one…or multiple?

Can a weapon have more than one Grip?
More than One Stock?
More than one Foregrip?

Again…only interested in what the game can actually provide in a drop.

Not sure if all type of weapons, but Body and Barrel can have three accessories. One stock, grip, foregrip etc.