DND_Reborn
The High Aldwin
We've been stacking advantage/disadvantage in this manner since the start. Hasn't bothered or broken anything and since no one at our table is a crazy multiclassing min/maxer crit hunter, we have yet so suffer such an issue. Frankly, if someone went through all the trouble to do it, I doubt our DM would care. 
In other words, house-rule on!

In other words, house-rule on!
