Depends on the vitamin. Does a calmer digestive system mean no nausea? No diarrhea? There could be something in the multi you don't need that excess of was causing problems.
There are lots of varying views in the Paleosphere on the necessity of excess supplementation. Some say have your bases covers, some say it's not needed. I say do what works for you.
I take what I need and sometimes what I think I need. Mag citrate for bowels, zinc/copper for experimentation, Vit D for deficiency.