Here is an example. If you click on 1stButton, it shows you Goalie and Referee. Then click on Goalie and you won't be able to click on Referee (or make it go there anyways). Vice versa is a little weird as well.
I would assume that since the Actionscript is the same along the whole timeline after 1stButton that you should be able to click on either button at any time while they are shown.