When I start a new connection then automatically a new pane/tab on the right is opened. This tab contains a sub-pane/with multiple sub-tabs (see this snapshot link: http://img841.imageshack.us/img841/7218/duplicatepane.png or attached picture
As you can all these tab are somehow duplicate because they already exist on the left side as well.
Can can I permanently suppress auto-opening these duplicate tabs?
I don't know the answer, but that has been happening to me also. I've just been closing it and opening tabs I need.
For me I think it started after I changed Tools | Options | Environment | General > 'Action to perform at startup:' from 'Open Toad homepage' to 'Nothing'.