do females do the black dance thing when they spread their tentacles and turn really black. im not sure if i have two males or one female and a male.

Maybe 2 females??? lol

It's very very hard to sex bandensis, and if you check Righty's site out, you'll see how he does it.

As I keep mine in a breeding group, it's obvious sometimes which are male and which are female. I feel I can take an eductaed guess now after watching them for a while, but I feel there is now obvious diamorphism between sexes.