Hi alisonmallon,
As per the ATO's STP guide, on page 44 the error description is listed as 'Where multiple full file replacements have been lodged in quick succession' and their advice is to wait a full business day, then resubmit. In this particular instance, if you have further questions I would recommend you speak with the ATO as while we are here to support you to the best of our ability, in this particular case we would be unable to action anything in regards to this specific error.
-Kass
