Lets go back to the beginning where you said
(a) download the latest version exe on my desk top
(b) download the file on another system
The result being (a) is not updating and (b) is updating.
Now, if you are starting both downloads from the same location then one can’t be an older version (even though that is what the message implies) and the other be a newer version, therefore it’s going to be suggested that the desk top computer has got a “brain snap” with regards to Manager.
Therefore it is suggested that via Control Panel uninstall Manager, then go to the programme file location - users/(user name)/appdata/roaming - and make sure the folder is empty, in fact you could delete the folder. Shut down, wait a few minutes and start (not just a restart) the computer and start download as a clean (new) install.
The data files location (unless you have relocated) - users/(user name)/appdata/local - should be unaffected by the uninstall - however either do backups or copy the above folder on to storage device as additional protection.
IF (?) the message returns then its not the download but a “brain snap” within the desk top.