Merchants can have few stocks of the same item
As you can see in the image, trader has two stocks of Cyrodiilic Brandy. First one, of 5 pcs, is in his crate and is not restocking; the other one is restocking in his own inventory. In vanilla he has a single stock of 8, and spends its restocking part first (so if you purchase 3 bottles, he will have 8 again; if you buy 4, he will have 7). Don't know, maybe it's more of a feature than a bug, but without any indication of difference between stocks it looks strange.
(RM-2842 from redmine: created on 2015-08-10 by Denis Smirnov, , closed on 2018-05-27 by nobody, duplicates #1933)