Yes indeed. Originally both of the my reservations were at the Sheraton (due to the Marriott being 2x the price). A few days before my stay I received an email from the properties:
"...A warm welcome to our dual branded hotel, the Sheraton Frankfurt Airport Hotel and Frankfurt Airport Marriott Hotel. We are glad to inform you about your upgrade to our premium product, the Frankfurt Airport Marriott Hotel.
....
With kind regards,
Nick Zilinski
Hotel Manager