It could be downloading the same movie if it's having connection errors with your seedbox. I have everything running locally and run into this occasionally. The radarr logs should tell you what happened.

The other possibility is your quality profiles aren't setup properly. When you view a profile, the way the formats are sorted (4k remux, 1080p Blu-ray, 1080p Web-DL, etc) tells radarr the priority of qualities you want and it'll keep upgrading until it hits the cutoff. With brand new content, there's also a delay setting so that it'll wait a set amount of time to download something when it first hits the internet (e.g. wait 30 minutes before choosing a file to allow for better quality uploads).

And as the other user said, with media that you already had when you setup radarr, you'll need to manually import it.