To answer your original question...Yes! If in fact one click equals one inch at 100 yards it will equal 1/2" at 50 yards. With adjustments that course it sounds as if you have an older Redfield scope.

How your 50 yard (meter) zero will effect your 100 yard zero will to a large extent be determined by how high above the bore line your line of sight is. (It is best to confirm your 100 yard zero by actually shooting at 100 yards!)

Good luck!