I do not know your background but when it comes to analysis to determine whether two or more documents were written by the same individual, you do not know anything about that which you speak. While you may not like either Iseem or Mystery, in this case, it is a lie not supported by the facts to suggest their posts have been penned by the same individual. You are engaging in the exact deception of which you accuse (with malevolent moral outrage) each of them.
If you wish to state your opinions it is usually a good idea to have facts to support those ideas. In this case, appropriate DD would be to take the posts of both Iseem and Mystery to a linguist at a local university and ask her or him to analyze them. You will be told what I am telling you.