What version of cr2hdr are you using.
Latest, with date-stamp of Dec 7, 2013.
IIRC, I did update the version of ExifTool that came with the earlier bundle of cr2hdr.zip
Could they possibly be "out of sync", and I "shot myself in the foot"?
There were some other oddities ...
* Out of several hundred pano files, those with problems weren't sequential:
* 4055 then 4060 then 4061 and then 4067
* Create times were an hour after the last actual shutter activation
* ExifTool refused to rename the Lens model from "Samyang 14mm" to "Canon 35mm"
* And I'm unclear how a file with EXIF of 35mm got changed to Samyang 14mm
Also, I wonder if this is possibly related to the issue of renaming the Dual-ISO files to _UAL_####, which has the warning of "Not reliable". My somewhat convoluted workflow treats _UAL_####.cr2 differently than _MG_####.cr2