Hello,
Seems like there might be a Hamachi registry key stuck here: HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products
Once you're in that Key just search for Hamachi, if it finds a subkey feel free to delete it (please do an export of it first, in case you delete the wrong key), once the computer has restarted you'll be able to install Hamachi.
Best,
Vitor | Technical Support Representative
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