Making two of the exact same bead is a daunting task for me. Sometimes I get the design right, but not the size. Other times they are close in size, but the designs are totally off.
Another lampworker once told me that for earrings, at least there's a head in between the earrings, so slight differences aren't that noticeable. That's a good way to look at it.
I've recently been making my "pair" beads on the same mandrel, and that is a huge help in getting them to match up better. It's trial and error, and what I've learned is to make the top bead first. That way if you need to flatten the feet or anything like that, you won't have to avoid another bead below it. Also, keep flashing the finished bead in the flame so it doesn't crack while you work on the second one. That is a very important tip. :)
Here are a couple little pairs I made recently. I think they came out pretty well.