The MTO just sent me a new license. It was issued the day after I got my M1 but it's identical to my old one. What gives?
Your M1 licence is only paper. M1 status is not listed on your physical card, only M2 and M.
The card you received is likely the new "barcode" card replacing the old magnetic strip cards (check the back).
Think this happened shortly after I got my M1 as well. I just shrugged it off... keep your temporary paper license on you until it expires, even if you get a new card in the mail. When you get hassled by cops it gives you a bit of noob cred and they might be more inclined to let you go with a "warning". Worked my first two pullovers. Third time I had my new card and the officer seemed skeptical when I told him I just started riding and he wrote me a ticket.