Interesting. When I see my trade on the tape it's

Interesting. When I see my trade on the tape it's the number of shares that have changed hands in one transaction. At the same time, I've also seen what some call "mirrored trades" where the MM will quickly put a buy or sell of the same amount, almost instantly. Who it was I have no clue, was it a legit trade? Or was it naked? Sometimes it happens, sometimes it doesn't. But as far as I know, the daily volume is just what's changed hands. Not divided in half.