Equipment bug

so i recruited another dwarf and started putting things on him, rather than taking off his current rusty knife i just dropped new weapons ontop of it and the knife changed places, then in the last slot i try to drop a weapon over the knife and the knife vanishes and the space becomes blank. I switched character profiles to another, then back to him, the item space was available again but the rusty knife was gone, so i put on a spear and left.
Then i went back to see if the knife was back and it was back, back in my hand and the spear in my bag =/

 

This only seemed to happen in Startington, it didnt happen while re-arming for a dungeon