As far as I can see:
1- WP Dashboard > Appearances > Themes > manage Themes does not display the version of the installed themes.
2- WP does not have a mechanism to have different versions of a theme to co-exist and switch between the two.
If I'm wrong, I appreciate if someone shows me how the above can be achieved and/or the version number be seen?
The reason to my request is simple. I want to be able to test the updated theme before committing on it. Often I need to make alterations to a theme which is later updated to have the alteration inbuilt. At present the only option I can see is to over-write the old theme and if the update failed to recover from backup.
Whereas if WP allowed two themes of the same name but differing versions to co-exists the process would be very simple.
Thanks in advance for suggestions.