Unless a player is on leaderboard, there was really not much of a reason for them to match against themselves unless they space out and play their alt even if their other account was still searching for a match and resulted to match themselves. Either way, both accounts use 2 their energy but only won a single match when they could have win both if they match with other players. Of course the opposite could also happen and they could also lose both match but we can't really know. At the end, matching with an alt account could be less likely to happen with new players adding more liquidity which is what we need to focus on.
Regarding brawls, I think there are more factors to consider since there are times that assigning frays is decided by the guild leader/co leader and also based on what collection those accounts have, making the frays they can enter pretty much decided. I also think that 1 win/loss due to wt in brawl does not have that much of an impact to the overall result of the brawl since brawl result depends on the overall performance of the other guild members.
Now, for the tournaments, while I like having tournaments free to enter, if there are entry fee just like before just like before, this will disincentivize people from entering with multiple accounts.