Picked up 17 random 1971 Topps checklists at a thrift store today for 10 cents a piece and noticed this variation, which does not appear in the OPG or my 2003 annual.
1971 Topps #161 (coin checklist): Two have light gray backs with green borders, one has a almost shaded green center with a green border.
1971 Topps #161 (coin checklist): Two have light gray backs with green borders, one has a almost shaded green center with a green border.