Last year REA auctioned off a handcut Plank and a few other "scrap" cards from a find. REA likely assumed these were cut from two sheets(Piedmont 150 & 350) along with the Plank (at the time all Plank Piedmont 150s were handcut)
http://bid.robertedwardauctions.com/...x?itemid=18490
The Lake example from the 2012 REA auction has similar markings on the back as the previous years handcut lot (Manning), same find?, same consigner? It's likely REA made a similar assumption on being handcut from a sheet. Secondly a few of the cards show signs of missing an ink layer which along with being handcut would suggest it is a printers scrap.
http://www.robertedwardauctions.com/.../2012/159.html
