Something weird happened to me the other day... I just claimed the top 2 exp buffing potions(52%) and stacked them. I only took 2. I used one of the two TS potions and I only thought they were 15 mins or so and didnt see an icon and I did some combines, got a level and left the zone. The next day I was TSin again and saw that I had 2 of the TS potions again. I am using them from inventory. Not sure how I got the second but if that is a bug, so much for the single dose stacking idea. Maybe there's something wrong with using them from inventory.