Sometimes, while double carrying, instead of setting down a weapon to climb a ladder, the weapon will be held in thew right hand and remain there while, and after climbing the ladder. Sometimes setting down the weapon will normalize conditions, but sometimes the weapon disappears; sometimes it is possible to climb back down with the weapon in one hand, set it down, and pick it up again normally.
Sometimes vaulting while sprinting will cause player to do crouch vaulting animation, and remain crouched. When double-carrying, this animation bug will cause the weapon in hands to be held in one hand after completing lowered vault animation. Setting the weapon down causes it to vanish when this happens.