Enemies with duplicate weapons?

[JDR13]

I've been noticing that sometimes, when I kill an enemy, he'll drop his weapon on the ground, but then still have another of that weapon in his inventory.

 

Is this a bug, or was it actually intended to be like that?

 

I'd like a mod that prevents enemies from having these duplicate weapons, as I feel that it's both unrealistic, and makes the game too easy in regards to loot.

 

 

*Edit* I just realized this only happens if you take the weapon on the ground first, and then loot the body. It doesn't happen all the time. Definitely a bug.