I have a constructive suggestion!
There's no need to flip a coin – there's a better option!
So, let's say Vasya and Petya are playing. They need to at least start the game. And at some point, they decide they can't finish the game for some valid reason. They save the game and turn to the judge. The judge loads the save and looks at the thieves' guild information. Whoever is listed first in the "kingdom army strength" field wins!
By the way, in all the years you've been playing "Heroes," have you ever seen a tie in the thieves' guild? I haven't!
I understand that some will strongly oppose this option, but my job is to suggest it.

Partially for, partially against.
Against – Leader has already written about it; I don't see the point in repeating it. I'll also add that I recently played with a friend. My army strength was higher, but I lost in the final battle.
For – because, for example, in football, hockey, and other sports, the game lasts for a certain number of minutes. And the phrase: "We would have scored more, but we ran out of time!" sounds naive.
Therefore, I believe that in Heroes, the game, for example, should last until turn 247, and then the winner is determined by some parameters.
For example, in boxing, the number of rounds and time are limited, and in the absence of knockouts and knockdowns, the winner is determined by points, and if the opponents have an equal number of points, it is up to the judge's discretion. In football, they take penalty shootouts after the game.