Originally Posted By: Darxim
I think the stacking bug is caused by items that have different graphics despite being otherwise identical.
I don't think this is the case. I have three stacks of regular healing potions in my inventory, all with the same graphic and descriptions, that don't stack. The only difference is that one stack is stolen.
Basically the RootTemplate of items must be the same to make items stackable. D:OS 1 had some items (skulls for example) that didn't differ in visual appearance but had different root templates, so didn't stack. Maybe a 'stolen tag' (don't know how if they tag those items or just use a database in Osiris, probably the first) prevents items from stacking with non-stolen items, which would make a lot of sense.