I was looking through the list of available dragons I had to summon and started the summoning process of Founder Dtagon, which I already have

Is there anything that can be done about this?

You can try to contact support but I doubt that they will reverse it. I suggest while your ticket is active leave the egg in the summoning tree until they say whether they can help or not.

@putputter you could also just level up to 30 (around 500k in food) and revoke him for 100 orbs