using 2 different vials?

[pdxboner]

Sometimes one vial I'm using has so little, I wont get a full does (I'm currently at 22 units). I typically have my next vial on hand. I often wondered, can I inject the remainder from one vial, and then inject (with a new needle of course) the needed remainder from the 2nd vial. I've never tried that. So lets say I pull only 10 units from vial #1, and that draw empties it. Then I pull 12 from my new vial. Will that work. any downsides, except two pokes?