I got a new Chartplotter and Radar and it came with a PG700 and now I am ordering a new 700c and it also comes with a PG700. Is there any advantage to hooking up both PG700 to the network?
Two PG700 on the network at the same time do not increase performance. Simplest to only use one.
You probably are referring to the modern 711C autopilot, that can be purchased with different bundled components and you may be able to save money by purchasing the autopilot without the PG700.
You can have both connected but you must change the instance number of one of them so they don't step on each other on the bus. I agree that having two connected offers little to your system.