I recently noticed that some of our map exports to PDF are producing 2 complete copies of the data frame in the PDF file.
This seems to be more likely with CMYK or high-resolution exports, but I suspect that the When of the export is the main culprit, as a random check of older exports does not find this problem.
Using 10.1 Advanced to export, exporting layers not attributes, and using Adobe Pro 11 (buggy) to open.
Any one else?