I know, andy, its a visual bug
I have 182 % item drop according to the screen (all of my mercs have rings and amulets with bonus to item drop) but the maximum you can have is 100 %, the system simply adds up the % from all item drop items, instead of displaying that the chance is already maximum.
Actually, if you go on to the next battles of the multistage dungeion, it gets fixed somehow magically
I ll move it to texts anyway, I dont think that it actually gives you more than 100% item drop...unfortunately