If by that you mean two biners with brake bars in them.  Without a long rack, I don't see how anyone could get the friction control necessary to go down a 75 lb. rope (650 ft).   The handbook of single rope technique, "On Rope" by Bruce Smith, has a picture of a double biner setup with a big 'no' symbol over it.   Some people use bobbins or petzl stops but I don't know if they are suitable for long drops or not.