Personally, no I don't worry about it. Sometimes I've ended up playing the same 5 people on a few different tables at the same time.
That's just what happens when everyone wants to play more than one table at a time to get more hands in.
I can understand watching for collusion... but I've never felt like I was being colluded against. And if they are they're very bad at it.
In general, bitcoiners are bad poker players. I walked away up at least $80 and don't plan on returning because even though hackers are bad poker players, they still have the upper hand by cheating.
I'm willing to bet you are one of the people who is involved in collusion on the site otherwise you wouldn't be so pro-cheater.
How can you make such a large generalization when you just "walked away up $80"? Sounds like you've only played poker once or twice, $80 isn't really anything in the long run. I don't play online often but I cash in about 70% of tournaments I enter in at casinos, your statement just leads me to believe you lost a bunch of money and you're looking for something to blame it on. The best way to avoid being cheated is to not play online poker.