Visits Web Page - Allow Constraint for No Duplicate Page Visits

I have a "Visits Web Page" trigger, and I have a constraint on the number of times (3) and the date of activity (past day) but the leads will still trigger even if they visit 3 of the SAME page. It would be great to have a constraint that says 'only trigger for __ (in my case 3) different web pages' not allowing for the trigger to activate when a lead visits the same page multiple times.