Mark and Nikita inflation

You can be either a human or a furry, as you wish.

You have two pets (call them whatever you want), they are both the same breed but have different fur colors, Mark is gray, black, orange, and Nikita is white, yellow.

And now they're having a battle, they have pumps that inflate each other, Mark inflates Nikita and Nikita inflates Mark, they have one rule: if one of them gives in, the winner wins, or they don't stop until they burst.

Mark: I will win you, I'm tougher.

Nikita: No, I'll win, I'm tougher than you.

What should I do, stop or not?