Generally before promoting any user, the promoter will check the history of the creation to verify if they are valid (All blocks created and destroyed contain user information), if time logged on the server or build/delete count does not correlate with what is presented then of course we will look further into the matter.
Naturally, users do slip by from time to time, so if you ever feel another user has blatantly stolen your work and are well aware of it, then by all means, report it. Doing so will greatly help us out in moderating the ranking system and prevent those who have ulterior motives (To grief ranked worlds, to get a free ride, etc.) in gaining rank.
Cheers.