All existing signatures are displayed as tiles on the Home page and/or within folders.
If you want to create a new email signature that is similar to an existing one or make a backup of a signature before making changes, use the Copy option associated with the relevant signature tile:
You are prompted to choose a location for the copied version - you can choose to add it to the Home page, or an existing folder:
Having selected a location, an exact copy of the email signature (including any user/group settings) is made in the required location. The title of the copied version is preceded with the text 'Copy of...':
From here, you can modify it as needed (for example, rename the signature, edit it and change who is to receive it.