What should I do when I'm rewarded with an evolved arcadion?

I keep getting rewards that are second evolution arcadion of first evolution arcadion that I have already captured. Should I feed the second evolution one to a different arcadion and just wait for my first evolution one to evolve, or should I keep the second evolution reward and trash the first evolution that I captured?

What do you guys think?

It’s most logical to feed the second evolution and wait for the first one to evolve provided both are the same grade. That way you end up with the same monster in the end but get some bonus levels in addition. 

But if I would get the final evolution form and it’s an extremely high level already I’d probably keep it out of sheer laziness. 

Keep the one with the higher grade. If they are equal, keep the one with a higher level.