They were different revisions, the color highlight sheet was the 'new' version for the 1970 model year, it seems to have first appeared about mid-model year.

There have been countless cases of '68 & '69 revision sheets found in 1970 cars as well as blue & white & colored sheets found in the same cars.

The older sheets were often used up in the trim shop because the interior code was in the same spot as the newer sheets, so it was a great place to use up the old leftover stock.