So far, the brown LENOX cards that I know of are found on subjects in the 350/460 or 460-only series.
In my opinion, these cards are the result of errors in the printing process. Perhaps, a color blind printer on the late nite shift mistook the brown ink
for black ink and cranked-out a sheet (or two) of these
And, then there is the mysterious "blue OLD MILL" card of Walsh.
This T206 MONSTER never fails to surprise us.
TED Z