There is actually a good Oracle Support article on this error. There can be a variety of reasons why one might encounter this issue. Occassionally the values in the Counters table get out of date. Sometimes you’re attempting to check in a new piece of content with the same Content ID as an existing piece of content without knowning it. Oftentimes this happens if you are integrating with Content Server and are attempting to generate a Content ID.
Once you’ve have fixed your core logic issue you may still be left with a “corrupted” piece of content in the system that you need to get rid of before you can make a fresh start with your updated code or process. To take care of this situation:
Step 1 – Open Admin Applets -> Repository Manager
Step 2 – Search/Filter to find the offending Content ID.
Step 3 -Delete this revision in the system.
You should now be able to checkin content normally again without this error occurring.