I'm confused as why your form submission would trigger a revisit, is both built into the same smart campaign or seprate?
If they are sepreate smart campaigns, If a lead has visited twice before and visits a 3rd time and that 3rd visit also filled out a form and you have 2 smart campaigns with Triggers in real time - yes, that sounds expected behaviour by your design.
You have a challenge here, question, how important is the visit alerts to be in real time? Forms yes as its showing explict intent.
Think about using a filter (not trigger) to your multiple visits smart campaign and set up a schedual to process once a day to fire alert emails.