So I've tried this on multiple browsers now. All have bad/broken results.

If you view your reservation on the Marriott website and click on "Print This Reservation" it puts a javascript overlay of the reservation on the main page. There is no auto print or print button... you have to use the browser print.

Doing that seems to confuse how the browser prints, duplicating the same first page of the overlayed reservation 3 times with the rest of the website pages in the background. Result is missing or unreadable reservation info.