Hi Jim,
Wouldn't both the lighter shades of Sovereigns and Piedmonts be found with certain groups of players because those players were on the same sheets where the ink was applied lighter? Kind of like T210-3 "orange" borders. The orange color was not purposeful. I won't pretend to be an expert on the printing process, but I've always assumed it was more of a quality control issue. Been wrong before though.
Rob