Make a boolean with an index for every race (I call it boolean_race[]).
Now, for the dialog, set the buttons like that

Actions
Now for the buttons, after peforming the actions after a button is clicked set the respective boolean to true
Like:
clicked dialog button == Button 1 -> set race_boolean[0] = true
Now if the boolean is set to true, the engine won't set up the dialogbutton ;)