The best advice I've been given on this issue works, but it is... less than ideal: drop the already enchanted items at the font (my precious nukes!) and drink an invisibility potion to avoid attracting attention.
I've tested that items stack with the most enchanted one on top and then in order of number of enchantments, i.e.: +6 > +5 > +1
I would like them not to form a stack, but if this is easier I propose a simple(??) change: reverse the sorting so that the least enchanted item is always on top. This would allow:
- not having to put things on the floor
- be sure that the stack is always well enchanted if the one at the top is at the maximum