I am not sure this will help much, are your users creating a new document or using a create follow up - which is a new document but could be importing fields from the original transaction? If a create follow up then entries would be in table CRMD_BRELVONAE with the guid of the orginal and newly created document. The copy rules / copying routine in the IMG could be bring the fields into the new document.
If you can -recreate in your dev or qa system, you can always set SU3 parameter WCF_IGNORE_ENHANCEMT = A to validate you do not have some enhancement that could be the root of your issue (that parameter turns off customer enhancments)
Regards,
Glenn