If there are multiple campaigns targeting the same group of users on the same page, the users will see the campaigns on the order of priority of the campaigns. In the VIEW CAMPAIGNS page, the campaigns at the top are of highest priority, and the campaigns on the bottom are of lowest priority.
If a user is shown 2 campaigns on the same page, the user will see the campaign of higher priority today and will see the other campaign next session.
Multiple campaign display is dependent on the frequency of the campaign and the throttle of the global user settings. Higher frequency will increase the number of sessions that the campaign will be displayed. Higher throttle will increase the number of campaigns that will be displayed per session.