An associate of mine recently discovered that we had two App-V 5 packages with the same GUID. This was not a case of mistakenly adding onto an existing package or anything weird like that. These were two new sequences made by reverting the snapshot on the virtual machine back to clean. This was a strange predicament because these are supposed to be randomly generated GUIDs with little chance of ever coming across the same GUID again. As we dug into it some more, we found two more packages with similar GUIDS, but different from the first. In total we have four sequences in our library that had duplicate GUIDs.
A quick search of the interwebs brought us to an article by Tim Mangan (godfather of App-V). I recommend anyone that will be sequencing applications read that article, but to sum up- Don’t take a snapshot of your virtual machine with it powered on. Make sure your snapshots are taken with the machine powered off. This will ensure the seed that creates the unique GUID will be different than the one that was saved in your snapshot. It may add a few seconds to your process, but its worth it in the end to avoid this issue.
Read more here: TMurgent