If I open the same document in okular, even if that is not edited, it does not open the same window, but opens another fresh window. So, when I open a file, even if it is already opened, duplicate tabs open up, without redirecting to the same window.
hi, welcome.
you can only have one instance of a document open in an okular window which is why this feature request would be a QOL improvement
however you can open the same document in another instance of okular, as you have noticed, if you have open new files in tabs left unchecked.