Please Offer Your Color Opinions On These 599 Issues.

I see a bold difference, but my eye is untrained.

Used stamps go through quite a bit of stress and environmental changes.

Carmine and dark carmine. There were 57 plates used for this stamp, and billions issued. So carmine has several variations of shade, most of which are not listed because they are considered minor variations.

This stamp was the workhorse coil issue during the 2 cent first class rate period ending in 1932, but was still a useful denomination afterwards.

Gary Griffith notes in his "United States Stamps, 1922-29" volume published by Linn's in 1997 that neary 25 billion (yes, Billion) of Scott 599 were issued. And goes on to note "Although only two shades are listed today (carmine and deep carmine), this stamp was in production for more than 16 years and appears in a variety of shades. ... This stamp went to press many times and there is certainly a light carmine shade."

And of course there is now 599b, the very uncommon "carmine lake", which was recently added to Scott's U.S. Specialized catalog in 2007, 2008, or 2009.

I also agree with the direction Parttime takes, of not trying to read too much into used stamps of unknown use/abuse histories. I would conclude your two stamps are well within the normal production range.

Red is particularly susceptible to fading in sunlight