Modules on weapons bugged?

[Geistermeister]

Are modules on weapons meant to be excluding towards each other or are they simply bugged? When you try to apply a forward hand grip on a GP37 while it already has a laser module on it the lase module disappears (also cant be flipped back onto it, so at least one bug is definetly here).

Is this intentional? Because I do not see how a grip under the weapon thats attached below it can possibly exclude the use of a laser module on the side of the barrel.