Yes, two staples is okay to microwave. Really. Alton Brown said so, and I've done it. Pop on!:9
ETA: Alton Brown received so much angry mail about this that he wrote it up in his first cook book. Here's what he said:
QUOTE---------------------------------------
THE GREAT POPCORN CONTROVERSY
I wish to defend myself against the charges of microwave abuse. A couple of years ago on a certain television program, I made microwave popcorn from scratch, using plain popping corn, a little olive oil, and salt in a small paper bag sealed with not one, not three, but two standard office staples.
Well, despite the fact tha I had tested this in no fewer than ten different ovens, and despite the fact that the product was delicious and cheaper than dirt, I received tons of angry mail. People were just sure that their housed would explode.
No. Relax. It's okay.
As long as you're using a microwave oven with a turntable and you don't place the bag where the staples can rub against one of the walls, nothing bad will happen. This is because the staples have very little mass and they are shorter than the microwaves themselves, which