This error occurs when your ADMX Central Store or Local Store has two ADMX items that overlap with the same value.

There are two articles you can read to fix the problem permanently:

1. https://support.microsoft.com/en-us/help/3077013/-microsoft-policies-sensors-windowslocationprovider-is-already-defined And
2. https://jorgequestforknowledge.wordpress.com/2016/10/13/namespace-already-defined-as-the-target-namespace-for-another-file-in-the-policy-store/