I re-use wire and pipe all the time.
Just have him check the wire real good as you're going back in the hole for "bruises". Nicks, cuts, kinks, etc.
Porky suggests turning the wire around so the old bottom goes to the top and vice versa.
14-ga wire sounds too small....Might double check to see that it's 12ga. I never use 14 ga even if it's in spec....always go with 12.