As you probably know by now, Microsoft-based operating systems use SIDs (Security IDs) that are generated as part of the initial setup of Windows. If you have more than one computer with the same SID, this could cause problems, and cloning a computer (either physical or virtual) without re-generating this SID can cause SID duplication. Please read the following article if you need to learn more about this issue:

Do not disk duplicate installed versions of Windows

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