IDB5 MA throws cd-existing-object error after a failed export

Using IDB5 (5.0.3 - not yet confirmed if this is still an issue with 5.0.4, but looking at the list of fixes, I suspect so).

Exporting a user to DET's CAMS system, for which a connector has been written. In Dev the system uses a dummy web service front end to allow users to be exported. If an export occurs when the service is unavailable, then an error is returned to the MA (in this case a missing end point error). That is as expected.

At this point, an entity search in the adapter does not show the user as being there.

Starting the web service and repeating the export from FIM, gives a cd-existing-object error.

To enable the export to complete successfully, it was necessary to run an import all on the the IDB5 connector - even though this reported no pending changes and no change to the number of adapter entities.

Any idea what might be going on?