Duplicating a theme to use multiple Index Templates

Hi guys I’m trying to use different index templates for different sites on my mutlti site wordpress. I thought I could do this by duplicating my theme, renaming it and adding it to the themes folder so I can edit the second theme’s index and use it for another site on the network. For some reason the second renamed theme folder isn’t showing up in the list of themes in the admin. Is there something I’m missing with this process?

Thanks!