My dentist fitted a double crown to my back teeth. Is it normal practice to file down my own teeth for it to fit properly?

The dentist filed down my own top back teeth and my new crowns so much so the new crown now show the metal through, one right at the back filed down to show the metal and the crown in front of that has a spot of metal coming through the middle. I was surprised she filed down my own teeth as well because we couldn't get my bite right.