Correspondingly, we as a company reserve the right to cancel several identical bets and consider only the first one active as well as valid
We can't see if the same user posted those bets (username is hidden 100%) but even if it is same user he used different amount of coins for betting so that can't be considered as identical bets.
One thing I don't understand is why you deleted and edited his betting history without any explanation, and I guess only reason for him doing this split betting would be to bypass your maximum payout limit per bet.
I don't think we should argue, because you can't argue when bad faith is involved. Those 4 bets are clearly not the same bet. First of all, they are 4 bets. Second of all, "who will win the rest of the match" is not the same event as "full time result". They just decided that there is no God and it's not worth it for them. But people are not stupid. And it will hurt them for sure.