More than once. I've had stuff tone (done deliberately) sitting on the desk, while the "control" coin sitting on a stack of books on the desk did not. In most cases, it's not the wood but the coating applied to the wood - or the glue holding it together - which is the culprit. These days, my "desk" is a plastic folding table which I only wash with plain water. No more toning.
I use Caps Albums, which hold the coins in Ari-Tites and you can order custom printed pages for coins not included or made yet. Their ad says there's spaces for the 2014 Baseball coins. http://www.capsalbums.com/modern-commemorative-half-dollar-with-proof-album-2208