You can't stop someone from using alts in a f2p game. You can potentially limit the number of characters per account, but because it costs nothing to play, people can make as many accounts as they want. IP blocking or other such tricks? Don't work. Then only a few people make tons of alts that can constantly change their IP addresses. What about those on various forms of broadband that don't have fixed IPs? How do you track how many accounts they have?
Don't hate because you fail to use the same tactics as everyone else. There's nothing game-breaking about alts. What's game-breaking is the fact a player can train as many alts as one can produce for with just one or two characters. Straw Dolls, Shewbread, etc. all make great alt food.
Now, what the hell does this have to do with the OP?