Make sure that you're logged in under Xorg, as simplescreenrecorder doesn't work on Wayland (which is the default on Zorin OS 17). You can toggle between Xorg and Wayland by logging out of your account, then using the button at the lower right corner:
This has to do with how the software store searches and lists for packages. One the one hand you have the various package formats (Snap, Flatpak, Debian) which come from different remote repositories. When there's more than one option for the same package, it has to decide which one to display.
It's interesting that Snap shows first because, according to the default settings, place Debian packages should come before Snaps. You can check the order by running this in the terminal:
gsettings get org.gnome.software packaging-format-preference
For reference:
Sometimes you might see different entries for the same software because of how it's labeled. I specifically remember this example with simplescreenrecorder... I guess the labels must have been updated, or the snap plugin for the software store is buggy.