Is there any way to tell if a fork is from a single or double roller watch?

Yes If the Guard pin is straight up it is for a single roller.

Billy, Thanks for your answer, but it sounds to me it is for a fork that you know what watch it came from and bears true when you are putting it back together.
I'm speaking of a Waltham 16 that had no fork in it.
I know it's a single roller. I also have a pile of spare forks on the bench. How do I tell the singles from the double roller forks in this pile when they all have pins?

All the single roller pallet forks will have the pin at 90 degrees (vertical) to the pallet lever Patrick, the double roller will have the pin parallel to the pallet lever to engage in the lower safety table.

Cheers,
Bila

Thanks Bila,
That is the answer I was looking for.
Patrick