A duplicate object name has been found. This may occur if the SQL Server that you are registering is case sensitive but the case sensitive option is not set.
We am not using any case sensitive options or collations. In fact, usually I can just re-run the report and it works the second time. It would be great if it at least told me what object was causing the comparison to fail, but I have no idea what causes this.
I reported a similar issue about a year ago but never found a solution, though I don't know for sure if these are related.