Hi Andrea64,
This message usually appears where a business has multiple employing entities set up and the identical ABN is used for two or more of these entities. The ATO deems this as a duplicate lodgement and will hence cause the lodgement to fail.
Here is a more detailed article about this error and how it can be rectified.
https://support.yourpayroll.com.au/hc/en-au/articles/360000307336-STP-Resolving-Common-Issues
