I haven't faced this problem more than a few times. I remember doing two shots once, but I think i did it only once. On at least one other occasion, I changed the drawing needle, drew more T, and injected once. I was worried that I would get too much T in the syringe and would need to shoot it back in, thus mixing old and new meds in the new vial. To avoid this outcome, I wound up a little short or a little over and just went with what I had.