OP, if you don't realize all of those guys are the same person, you're blind. 
What is the problem if one person owns all of those accounts?
It won't make him any extra post...
You won't make more post no matter how many account you have.
I see no advantage for the sig program participants, unless the person wants to make fake conversion among his several accounts.
If that is the case, it would bring a problem to the program organizer, especially when the posts are not in English.
That would be very hard because other ppl would report them and mods would ban them... so I still can't see reason for that.
Mods don't care about multiple accounts.
Other people may not know the accounts belong to the same person.
By "fake conversion", I don't mean some gibberish, but something like the following:
Account 1: How can I do ... in site ... ?
Account 2: It is easy. You can do that by ...
Account 1: Thanks. What about ... ?
Account 2: Step 1: ... Step 2: ...
Account 1: Thank you very much.
Account 2: No problem.