Depends on the collision. Some times the back arrow is perfectly fine and it can be pulled out and used again. Other times the back arrow gets messed up pretty good and it can't be used either.
The last robinhood I did actully forced the back arrow's insert back into the arrow, screwing that one all up. The front arrow though seems to be no worse for wear, it needs the fletchings and nock replaced, but the UNI nock seems to have stopped the back arrow dead, keeping the front arrow's shaft straight.
So like I said, sometimes you can recover an arrow and use it again, but other times you won't be able to.
Rear Arrow.......R.A. Insert...R.A Fieldtip....F.A nock/bushing.....Front Arrow