Steve,
Both mirrors are front silvered. The spherical can be re-silvered by H.L. Clausing in Skokie, IL. (
http://www.clausing.com/main.html)
The flat mirror I've been told is not a candidate for re-silvering due to size and age, best bet here is a thin rear surface mirror you can get at a local mirror shop.
I'm restoring a Berkshire Regency and have had the spherical mirror re-silvered and I have a new mirror from a modern HD set to replace the flat mirror.
Chuck