Need Help With Singapore Printing Variety Sg#494/Scott#456

I found this oddity after soaking some old Singapore about 1 month ago. It was offset color printed for Singapore by the Japanese Government Printing Bureau.

The stamp on the right has degraded, or absent red and yellow ink in a large area of the stamp. That would not be unusual if a person used a glue stick with a bleaching chemical to affix the stamp to a cover. What is unusual is the sharp demarcation line of ink/no ink on the flower petal. It perfectly follows the design of stamp.

The only explanation that comes to my mind is that there were different plates for the reds and yellows. It just doesn't seem plausible.

Any thoughts/insights would be appreciated.

Bookbndrbob, you're right that it is unusual. I also noticed that the bee on the left stamp looks more real? Looks almost as if part of the stamp has faded, but that would be a bit far-fetched.

Peter

I have no varieties listed in my database.
all I have is
Leigh Mardon's printing has a rounded corner bottom RHS
and the Japan Printing Bureau came in normal and thick paper.
Litho.
I am always sceptical of abnormalities noted on used stamps.

One always has to be skeptical of abnormalities on stamps. I 've been burned too many times to think otherwise. This is an item I personally soaked, and I didn't notice the strangeness until I started sorting the dried, clean stamps.

I'm very open to the idea that this stamp could be a fake/fabrication. If it is, I'd really like to know how it was done.

In fact, several weeks ago, I put a damaged Singapore SG#494 in a chlorine bleach solution, just to see what would happen. The results were not like this item. The bleach faded the red, but did not affect the yellow.

If it were just the lower left corner, it would be easy to dismiss it as some chemical/light fading. But that does not explain the sharp white delineation that Bob pointed out in his first post...strange indeed.
Don