How to make Google Cal the "master"?

I have my Desktop and Laptop which I use to enter appointments into. Currently I have them both running CalDav Sync using the Mode of Outloo<---->Server (Two way). While this works it duplicates a ton of appointments.

Should I just do 2 different profiles on each device thus: Outlook--.Server (Merge) and Outlook<--Server (Merge) to stop this? Or what is the best option if not that? What I'm trying to do is make Google Calendar my "repository" for appointments and have the others sync to it, but I also need the devices uploading appointments I make on them.