Ideally, when you have the funds, you get another Garmin unit and you network the two units and only need one transducer. Of course if the transducer is mounted on the transom and you're on the bow, you're viewing old data.
I installed and linked my son-in-law's two Lowrance HDS units. He has a 10" on the console and a 12" on the bow. Initially he had just the one transducer, but we just upgraded to a second transducer on the trolling motor. He can now select which transducer he wants to view.
For my usage, I prefer the bigger, nicer unit on the bow as I spend most of my day on the water there. I don't need anything fancy or complex or even that big at the console.