Very improbable to get the same seat like that but here is simple explanation....similar to you thoughts on multiple accounts but not exactly multiple accounts on the same skin.
ACR, BCP, PokerHost, True......all run the 10$ od freerolls
sharing player pools so its possible these where different accounts for the same user on each of these skins or could be a big coincidence and they are different people. However its very conceivable that someone could hit the same seat if no one else is registering and no one is busting and its the only open seat then they would get sat there for all skins when they reg after busting.
It could easily be someone who has 9 or 10 accounts as well, who knows from our point of view but you could always report it as suspicious to support and I'm sure they would review it............we also have an acr rep on the forum that might be able to direct you specifically on where to go for feedback ......
Also I don't think I'd be too worried, I'd love to have a donky like the zle playing money games if he is going to fire a bullet from 7/8/9 accounts because its easy money for the rest of us lol