I like that look but all of my tails red match ya know
The color of the factory 2002+ center piece is darker; the degree to which this is apparent depends on lighting and camera settings.
My selection of pictures is limited, but here is an image just after the lights were installed - it's taken with the sun shining directly onto the tail light set, making for the worst situation to illustrate the color-difference, but you can see the change in shade between the center and side light housings:
It's not a kitchen accident, which infers that for a consistent appearance, one might be better served modifying their existing component, rather than installing the factory 2002-2005 part, which is darker.
To add to the confusion, the factory 2002-2005 side pieces are a color match to the factory 1991-2001 center piece, so many people doing the retrofit reuse their old center piece in a cost-saving measure, and create a consistently colored result.
I suppose another possible explanation are color differences between different batches of tail light sets for 2002-2005 models, I ordered all of mine from the same dealership, in the same order (but being a NOS part, that doesn't mean they were produced at the same time, or even in the same year).