From a purely technical point, how exactly will you determine cloned accounts?
Can't use email .. every account already has it's own email.
Can't use IP address ..
Where I live, there are 4 people, plus two neighbors using a shared wireless network, on 5 PCs. Two or more people could share each PC.
They ALL appear to the outside world as being one IP address. It's the nature of modern networking.
Where I work, at a large educational entity, there are between 8000 and 10,000 PCs that all connect to the internet, and EVERY SINGLE ONE of them looks like it has the same IP address to the outside world. PC labs could have an entire class sharing random PCs - using internal IDs from the PC won't work either.
Banning an IP address could shut off an entire class of biology students who have been assigned here for homework.
(Well, there are a couple of classes from certain school districts who SHOULD be banned, and BTW, all those obnoxious students had the same IP address. I keep logs too.)
So, without having to provide a passport or SSN or some other personal identifier to compete, how do you propose to control this?
BOINC went through this same exercise years ago, and gave it up as impossible to police.
Banning similar sounding named accounts might work in the short term, but if people want to do it bad enough, they will find other ways. Anonymous proxies are always good.
And in the end, you create chaos, hate, (more) animosity between teams, and it will all be wated effort that could be used elsewhere on a project that certainly can use all the resources it can get.
Just thinking out loud…