Hello Alexis, well, there is a reply to your question, but it is much more complex than running the update and use the repair function in Windows if something goes wrong.
You should cross-check the registry entries for the installed products and verify that they reside in the correct place.
If you didn’t move anything and your DAW was shipped pre-build with 7.5.20, I’d say it is safe to assume you won’t have any issues with the patch.
[EDIT: by the way, you should not be afraid of the patch - errors are not so common, and it case it happens, the procedure aborts and the current install is left untouched]