I don't know if Merc offers one but I know my parents Carver has a synch control. You flip a switch, throw the port engine all the way to WOT and then you control both engines with the starboard throttle. The engines stay within about 200 rpm of each other all the time. It works great and I often wished my fountain had the same set up. This is on a 1995 Carver so the technology has been around for a while.