Spain, Scott #56 Or 56A?

I'd like to call the stamp on the left (with pen cancellation) Brown and therefore Scott #56. The one on the right seems Dark Brown and therefore Scott #56. But #56a is supposed to be on white rather than reddish buff paper, and I'm less comfortable saying these two are that different (NB in second scan pen cancellation is on the right). Any thoughts? (I realize that judging color from a scan can be problematic.)
Eric

Any thoughts?
Just be aware a Black cancellation can affect the visual colour impression to the naked eye, that may be true also when interpreted by the scanner.

Personal opinion:
Both are on the salmon-colored paper. There is also quite a bit of variation to be found in the brown/red-brown printing, but the white paper variation should stick out like a sore thumb.

Here is a common block, from my collection, with the typical salmon-colored paper, and a vertical pair on white paper for comparison.

Nice example , Spain !

Thanks, Spain 1850. Your display settles the matter. Catalogues include so many subtle color variants. It's a pet peeve of mine. There are stamps of the same color that differ more from one another than do others that catalogues say are different. Fortunately in this case there's a paper difference that's decisive.
Eric

floortrader - Thank you! I love it when I can visit my Spanish collection.

EMaxim - You're very welcome!