Thank you for taking the time to share the details of your experience and feedback with the Community, although I apologize that you have not yet received a response.
We'll need a bit more information to be able to assist.
Please take a moment to review the information available here and post back to let us know what version and release of Quicken you are using.
If you have not done so already, I would attempt to restore a backup saved prior to the duplication occurring. Once in the restored file are you able to successfully sync or does the duplication reoccur?
So far, I think all is working well. However, is it possible to sync to the Cloud when using different PC's? I work from 3 different areas with 3 different PC's using the same Quicken account. Can I work from one of these areas at a time, sync, then sync from a different PC to get that information used at the previous PC?