I raised an OSS note. Here was their reply:
According with note 31771 - F5117 appears without reason" solution, you can use BTE 1110 for your own checks:
Solution:
ad1: you can implement the specified program changes (modifications) in all Releases if they meet your requirements. Prerequisite is the implementation of the correction descripted in Note 117691.
ad 2: from Release 4.0, you have the option within the interface concept OPEN FI or Business Transaction Evens of using the process interface '00001110 BUCHEN BELEG: double invoice verification', in order to implement your own checks (without modification).
Given this response, we will implement BTE1110 in function module FI_DUPLICATE_INVOICE_CHECK and exclude transaction codes FV50, FV60, FBV2, FBV0, FBD5, F-65 and FBD2. These are the parked document and recurring invoice transactions we use.
Note that in the function module it excludes FBVB - but this is not the transaction in our process so it does not help.
Regards,
Cheryl