Collapsing, affixes, and locators

In desultory testing of Zotero 2.1a1 over the past couple of days,
I’ve noticed some odd citation forms that come out like this:

Zachary & Vinton, 1993, p. 23; 1994.

It’s attempting to collapse the citations, despite the intervening
locator. My first thought was, “Well, that’s ugly”, and so it is …
but I’m not sure whether it’s actually wrong or not. I’m also not
sure how collapsing should interact with locators and affixes more
generally, and whether the constraints are uniform across styles …

We have a few months to sort this out, but I thought I’d mention it
since users are almost certain to stumble over it after 2.1 beta comes