If they are adept at separating their profiles from matches, assuming all accounts belong to the same person, one might also think that their IPs might be different. 
The style of the language can also be deliberately forged by the way it is written, with commas, paragraphs, capital letters, and so on. 
They can offer us the version that they are all friends, relatives, and so on. 
And until there is clear evidence, it is difficult to directly accuse people of fraud. 
This is quite a difficult job. If one person owns these accounts, one could applaud.