Xerox WorkCentre documents that have gone through the described workflow consistenly show a separation of the image into a lower resolution, jpeg encoded background, and multiple higher resolution monochrome bitmaps. This matches with the details found in the WH LFBC PDF. The cause of this is Mixed Raster Compression.
The objects are not identical and sometimes do or do not capture the full signature block.
The Mixed Raster Compression algorithm is incredibly sensitive to small changes. We also do not have access to the original document but even that would not have resolved the sensitivity of the algorithm. What we DO consistently see is a separation of the layers