Oddly enough, for my own personal curiosity, when you have both selected (as in your image) and you click one of them that is selected again, does that one select or deselect?
It selects just like normal.
This will be fixed in the next client update.
FYI, it is still not fixed with the build of yesterday (jan 24). Although it is maybe harder to select two buttons at the same time, it is still possible.
In the settings dialog, if you click on "Display a notification" does the extra radio selection go away?
Yes it does.
Also, I noticed that the bug happens when I "drag" the radio button, i.e. :
Then the two buttons are selected.
The Steam client has the same radio button image for "selected" and "focused." What you're seeing is focus-setting, which looks identical to selected right now but we'll change that for the next client.
Nothing extracted yet.
I can consistently get this bug to surface, simply click one radio then quickly (within around half a second) click another. I haven't been able to get all 3 ticked, nor have I tried to apply the setting with both ticked, but it's a problem nonetheless.
I'm running Arch Linux x86_64.