Canada 938 Background

I just picked up a random collection of stamps at our year-end Stamp Club Raffle. I saw these two low value Canada stamps side-by-side and see a distinct difference in the background. Both were kept in a Dealer's stockbook, protected from the light. It almost looks like the bottom stamp has a lighter background, almost scraped clean.

I'll take a stab at this one. There were several printings of this stamp which may account for the variety you've shown here i.e. they aren't both from the same source. In my catalogue they don't show the image of the stamp for each reprint so I can't be sure.

1) 30 March 1987, perf 12.5 x 12.0 untagged, rolland paper (uncoated) which came from the booklet 948a or BK92a
2) 01 October 1987, perf 12.5 X 12.0, untagged, harrison paper (coated) which came from the booklet 948ai or BK92b
3) 03 February 1988, perf 12.5 X 12.0, untagged, harrison paper which came from the booklet 1187a or BK96

The top stamp you've shown has to come from the 1187a/BK96 booklet (03 February 1988 printing) because that is the only one that has the selvage you've shown here.

The bottom stamp would've come from either the first or second booklets.

The dark spots on the left edge of the image in the lighter stamp suggests that it was either exposed to light or the printer was low on ink.

I would tend to agree with BlackJag, in that it appears to be a printer low on ink. I found another in my collection with exactly the same odd background coloring.