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There's a couple of conclusions that I would make. First Mars and earth may both be warming due to the sun, but it would be rash to make the claim in the first place (we have 3-4 years of data for Mars) and we don't have enough irradiance increases in the sun to explain simple correlated warming.

But there are certainly plenty of other ways the sun could affect both planets in different ways. One is the cosmic ray changes found in the lab to increase cloud nucleae. The atmosphere on Mars could warm by cosmic rays somehow too, but I have yet to hear any explanation of how that could happen (water vapor is out of the question).

The fact that both earth and mars have glacial cycles is an entirely different effect. On earth it is milankovitch cycles and Mars apparantly has them too. Those are due to changes in the planet (tilt, orbit, etc) not the sun and they are very slow. Powerful, but slow, so they do explain any significant amount of warming except over 1000's of years.