Hello,
Although this article has been out a while I thought that it was still interesting and did not appear to have been discussed yet on CCF:
http://www.numismaticnews.net/artic..._doubled_dieThe most important thing to realize is that per some cited verbiage below:
"A MAD Clash is a rather elusive class of variety in itself that has been catching on as collectible and we expect that hobbyists will continue to look for these and collect them."

fyi,
mdpmedia