I have set up a master page spread (see below).
The pages in my document are always rolling from right hand to left hand and vice versa. Using the master page shown above, I move the page accordingly in the page palette from right to left or left to right and the following happens:
The items that are no longer connected to the master page (because alts were required) are duplicated. Is there a way to only have one master spread (as opposed to mulitple master pages) and prevent the duplication of information every time a page rolls?
There are couple fo things you can try but it will lead to layout problem...
like You can remove the one master page from the master page spread in the pages panel but in that case the text on the bottom of the page (written in red) which has been layed out seperatly on right and left has to be manually adjusted and also margins on left and right which are different would no more be there.
Second is You are overirding the all master page items , rather then doing this just override the particular component like single text box or single frame using "SHIFT+CTRL"
I can't quite tell what happened in your screen shot, but it is typical of facing pages when you add or remove an odd number of pages that any master objects that were overridden remain on the page, and the other master objects for the opposite page are added back.