red color on coin

I have a Russia 2006 10 kopecks y-602
The coin on the left has a reddish color to the coin. hard to see in the scan.
Is it from the mint that way or did someone heat the coin to make that color.
Which coin should I keep?

Are there both non-magnetic?

Yes both are non-magnetic

There are some variations due to different mix
For example white bronze with excess of tin.
Your example might be not enough zinc that causes an oxydation of copper, but that's just an hypothesis.
These intense color variations are interesting, I would keep both coins.

For what it's worth, I have seen dipped coins take on odd colors. Apparently there is a reaction with the metals left from coins that were previously in the solution.

Might be for this brass coin, but certainly not the case for white bronze

I have brass coins from the Philippines from the 1960s that have the same red appearance, must be the composition of the metals reacting to environment. I would keep the yellower looking one.