Two more slots for Yriel's Fostering in Unique Stash Tab - one for each variant.

Some uniques come in different variants, while using the exact same base item, such as Volkuur's Guidance (Zealot Gloves) and Yriel's Fostering (Exquisite Leather). For the former there are 3 designated slots in the unique stash tab (one for each variant), while for the latter there is only one. How come?

It's understandable that some uniques have too many variants to give them one slot each (Atziri's Splendor, Dark Monarch), but Yriel's even belongs to the same "set" of uniques as Volkuur's (Prophecy), so why give it to one, but not to the other?