I think it is a little unnecessary when two tabs showing the same content( e.g showing the library at the same time). And recently I've noticed that MB can't remember where the library was viewed(in other words, the location of scroll bar) at some circumstances (e.g. first view at library ,then switch to inbox view ,edit sth at the inbox view ,then send tracks to library ,then switch back to library view, the scroll bar of library goes back to the start)
I think it make sense making sure MB won't show same content at two or more tabs(e.g. now I have library view at the default tab ,and then create a new tab, (the default behavior is to open a view of library ), MB will test if the content of library has been opened or not ,if it was opened, as I described before the default tab is library , MB then will activate the first tab, rather than open the library at the second tab)
Though I've a viewpoint of tab content, I don't think it is important ,because people may use this feature at sometime .
What important is that I think it will be good if MB can always remember the location of last view at library (Means after restart MB, or switching tabs, the scroll bar of library will still be where it was)