Where I wouldn't put it past them. The side by side picture above looks like it's more likely that one magazine used a higher quality printing method that resulted in deeper tones (the other (right) one just looks washed out--which could just be cheap printing) In other words, cheap bastards use less ink.

another thing could be that the magazines themselves might run ALL ads through filters for consistency.

an easy test is to find other ads in those magazines and see if they are all darker/lighter

I agree with envertigo, just look at the hair! It's pretty obvious that it's just the paper type/ink level and quality that differs in the images. The hair alone in the right picture looks a lot lighter too-- if they had been trying to 'whiten her up', they would have been careful to only hit her skin (unless they realized the potential blowback and intentionally kept it as is, but that's approaching conspiracy theory).

looks like they fiddled with the contrast more than photoshopped. on the left, where her hair is dark from the shadows.. on the right, it's brightened up, but by the comparative % of contrast.

in fact, all the shadows' contrast is softened, even the one under the arm.

Looks like the printer was off, not a photoshopped skin. The whole ad has a light saturation. Printing presses have individual personalities that need constant monitoring and adjusting., much like congress.