The MSI that you consider the original is probably not true. It looks like you are in a situation where PackageCode (GUID) A is installed, and now you have the MSI with PackageCode B.
Take MSI from you and run the following command:
MsiExec.exe /I foo.msi REINSTALLMODE=voums REINSTALL=ALL
This will be the MSI "recache" with the updated package. Then you can delete them either using the "Delete Programs" program ("Programs and Features"), or using the command
MsiExec.exe /X foo.msi
Christopher painter
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