Downgrading iMovie 10 to 9 but deleted both from Apps.

Hi, I use iMovie 10 quite uncommonly so I decided to delete it since it was taking a lot of space on my laptop. I deleted iMovie 9 as well which was still saved on my Applications folder after the update. Now I need to use it (stupid) but I wanted to download iMovie 9 instead of 10. I downloaded iMovie 9 from the internet but when I try to install it it says that I have to already own a verson. I redownloaded iMovie 10 from the App store and now that I try to install iMovie 9, it just says that a newer version is already installed which disables me to install it. Is there a way to get iMovie 9 back with this problem? Thanks