If F1 Grenade or Flashbang or Molotov are in a loot container and get replaced they create duplicated stacked items.

Eg

4x F1 Grenades will turn into 4x Crossbows stacked on itself.

I suspect this is because the following items are classified under the Weapon catagory ingame and come in stacked sizes

"grenade.beancan"
"grenade.f1"
"grenade.flashbang"
"grenade.molotov"

I suspect this would also occur in the tool catagory with
"explosive.satchel"
"explosive.timed"