I didn't see this in my demo perusal through the rules but an online squadron calculator seems to restrict each astromech to one per squadron. Can you take multiples of the same droid or are they unique like named pilots?

For the most part, yes. If they have a Black dot to the left of the name of the droid, than you only can get 1 of them in your build. The R2 Astromech and the R5 Astromech can be taken in any number you have cards for.

Ah, thanks. That sounds a bit more fair than a rebel xwing swarm with all R2D2s!

Note that this actually applies to any upgrade card, no matter what kind of upgrade it is. They could choose to release a unique torpedo sometime in the future if they wanted to.