Just to clear things up, 'nanners' is just a silly slang word describing male flowers. When ripe, they look like pairs of bananas hanging from a stem, and I suppose this is where the saying originated.

If you're diligent enough, you can probably pull most of them off of the females before they have a chance to release their pollen. But you'll have to keep a close eye on them, because as you can imagine, they're easy to miss. Also, if you can single out a stressor that caused the plant to hermie (light leaks, other undue stress, etc.) and discover that it wasn't genetics that caused it, you can also save the pollen from the sacs that you find, then later use it to produce feminized seeds.