you have two actors and one shared hit location?
Ok, first trace with one actor (no need to trace both as you want the same hit result)
then you have location of actor 2 and you want distance from actor 2 to hit location.
then do this: length((hit location) - (actor2 location)) that would give the distance from hit and actor 2
what I mean is: you just need 3 points in space:
1 - loc of actor1
2 - loc of actor 2
3 - the hit results of line trace (from one of the actors)
the distance from 2 points is the vector length of the subtraction of the vectors