It wa in the original.. I real pain.. Its almost like they dont like to stack when theyve been gotten in different zones.. Example cyseal, vs Silverglen...Its completely random, but yes, its been happening for a long time..
Sometimes they have different value, which is the case with Rubies..Same at 1st glance, but not so upon closer inspection..
Make sure you dont have the "Fake" arrows, which are part of the magic act in Cyseal Carnival...They 'look' exactly the same.. But when read carefully, the tooltip is something different alltogether..
I havent had many problems with same items not stacking since beginning the Enhanced Edition, but it was VERY common previously