When a duplicate or abandoned listing is created on eBay as a result of interrupted communication or incorrect market information, that listing is identified and removed by eBay Listing Synchronization.
When a SKU is matched to an active eBay listing during nightly synchronization, any other listing for the SKU on eBay is identified as an abandoned or duplicate listing and is removed.
The following is an example of how a duplicate listing can be created as a result of marketplace communication and then removed by eBay Listing Synchronization to keep your seller account in good standing with eBay's duplicate listings policy for fixed price listings.
In the example above, even though SKU mon0000000021 / eBay item number 1111111111 was actually listed on eBay, eBay did not confirm that the listing existed. Synchronization then identified the listing as abandoned or duplicate and removed it from eBay.
eBay Listing Synchronization overview