Thanks for the samples. The problem was that PixVue is writing the JPEG segment which contains the IPTC information (APP13) AFTER the DQT segment. This is odd. Normally all APP segments come before the image itself. ExifTool makes an assumption that that the APP segments come first to avoid having to buffer the image data while editing the meta information. This is true with every other JPEG image I have seen. You should suggest to the PixVue developers that they write APP13 before DQT.
But in any event I need to accomodate this in ExifTool.
What was happening is that ExifTool reached the image data and assumed that APP13 didn't exist so it created a new one. And when the existing APP13 was found after the DQT it was written as well. You were seeing problems with the other applications because they didn't like to see two APP13 segments (as you guessed by the duplicate IPTC2 record).
So I have made two changes:
1. ExifTool will now issue a [minor] error if a duplicate segment is created.
2. ExifTool now peeks ahead past the DQT to see if there are additional APP segments hiding back there. This should fix the problem when rewriting PixVue-edited images as they exist now. To repair any files you have already edited, you will have to erase all IPTC information then add it back in again with a new version of ExifTool.
I have added these changes to version 6.02 which will be released officially within a few days. If you want to test out a pre-release version before the official release, you can download the 6.02 pre-release
here.
Thanks for pointing out this problem, and for following up with more information.
About your copyright question. I'm not a Windows expert so I don't know how to create a Windows batch file, but this can be done easily in Perl (provided you know the character code for the copyright symbol). To which tag did you want to add the symbol?