This *undoubtedly* happens, is a prime reason many of us detest the "free HD" method of promoting the game, and is *definitely* cheating. It's against FPG and basically any standard of decency. And it's next to impossible for any of us to pick up on who is doing it, if the cheater is somewhat competent.
Even WIS would have a hard time catching someone who knew what he was doing. I also play an online horse racing simulation, and there was a guy there who started multiple different accounts, each tied with a different email and he was very careful about only logging in to each account from a certain place (home, work, one of several libraries, etc). Absolutely insane the lengths he went to cover his tracks. But he got caught because of how he was using those extra accounts; he would buy unworked, unraced horses with his main account, work them, then those who didn't meet his standards, would sell to these dummy accounts, basically eliminating his purchase risk. I would have never believed that people would work that hard to get ahead at an Internet game, but I've seen it firsthand, and since learned that it is something akin to a badge of honor among hardcore gamerz.
Some people say that's just "griefing" (a made up gamerz word that no literate adult should ever use, but I digress), not cheating. Those people are ridiculous.