There is a new error message that has been officially introduced for Google Merchant Center merchants. The new error is known as “Duplicate offers” and shows up when Google thinks “there are duplicate items in your data feed that should be removed.”

Google’s Ronald from the Merchant Center team said in a Google Merchant Center Help thread:

Some have indeed already noticed. You can just Google duplicate offers and restrict it to Google matches and you will see tons of complaints.

I assume Google has let the policy slide, but according to the policy:

Forum discussion at Google Merchant Center Help.