If you create more than one survey on the same page with triggers that all match, then we will randomly select which survey to display. If you have surveys A & B and both could be shown for a visitor we will randomly choose between A & B. Once a visitor sees A they will continue to see only A (if you have the setting of display "until they submit a response").
To prevent visitors from seeing too many surveys, once a visitor [sees/completes] a survey we won’t show them another survey until it’s been at least 72 hours and they have visited your site at least three separate times since.