My CS4 file opens up twice each time I open it -- here's an example - the original filename is "drawing.pdf", yet it opens as: "drawing.pdf:1" and "drawing.pdf:2"
I must've mistakenly typed the wrong key command or something...
You have created two views of the same file. Close one of the views, make a change to the other view and save. Then close and reopen and you should be good to go.
Thanks so much Larry!