That's a bug in the Matrix that will be fixed in next Erel's version, we are working on it. He is multithreaded but fails to put a lock on some tasks: so from time to time he finds himself writing the same tutorial. When this happens, they say 'hello' to each other, and the last one to click on the other's 'Like' button kindly leaves the thread.
It is also said that from time to time, instead of deciding who will leave, they decide to take a rest and go for some beers .