There are two types of listing data that appear on your website.
The IDX data from your MLS(s) and the listing data from CORE.
In property searches, both listing data from CORE and IDX data appear. Generally when there are duplicates only the listing from CORE will appear, though if you do not correctly add the MLSID to the listing you may show multiple instances.
On Company Listings or My Listings, only information from CORE Listings will appear.
IDX Data from the MLS is used on the websites in Property Searches, and can be used in CORE to initially create a Listing. IDX Data is not used to automatically update Listings in CORE.
Listing Data in Core is used for Transactions and appears on public websites on My Listings or Company Listings, as well as in Property Searches.
Proper function of Listings and IDX data requires correctly configured MLS IDs on Agent and Office accounts.