Actually, I'm more worried about IPSC scoring. They might think the 2nd shot is a miss.
I'm not even sure if my 2nd shot really when into the same hole as the first. But it is so unlikely that it didn't, because the target isn't exactly very small at 24" x 18".
Anyway, I'll use an even bigger target next time, just to be sure.
Here's my last target: 10 shots double tap @ 10 yards. I checked the target after each 2 rounds and verified only 1 new hole was produced.