No, but I have done it both ways. It is easier and faster to strip the old finish with furniture stripper like Formbys or Crown easy strip , Strip ease(they contain acetone and other chemicals) Use a old toothbrush and extra fine steel wool. The rinse with the acetone.
I use Minwax Helsman Spar Varnish in a spray for a finish . Your choice of sheen. I like satin. So when you spray it just hits the back also. Two to three coats.