In some cases, there's one GM over the properties and staff seem to switch back and forth at times for promotions, etc. so it would be convenient to use the same systems. [I even know of a case where a Westin and a Sheraton about five miles apart had the same GM. They were owned by the same real estate investment company and the extremely successful Westin GM from the time the hotel was built had his duties enhanced to include being responsible for major renovations at the Sheraton.]