Do they stack become range +2?
Also does that range affect on skill? (Especially AOE dmg) Or just normal atk?
From what i know it is stacking (and most ppl here will say same thing).
As for range it only affect distance from which heroes is attacking, or triggering skill (for not autoprocing heroes), but it is not affecting area of skill. If you think that area of damage will increase, than i have bad news for you. It will not.