My opinion, is that this is just a BIG coincidence. Reason I say this is because I am relatively new to CRH'ing, and up until last week I have never marked my coins. So last week I decided I should if I am going to be CRH player. The mark I chose Is almost identical to the one you posted a pic of, i couldnt believe it when i saw your pic, I thought it was my mark. Then I realized that #1 i had only marked ONE box so far, and also my mark is a little different. With the other three comments, Im guessing I was not the only one with the idea of marking them like that, (even though I had never seen a mark like that until your pic tonight....)