Add this function to your theme's functions.php file to prevent users from inflating the views count of a post or page by repeatedly hitting F5 / browser's refresh key.
Basically, this script will check whether the visitor has already seen a specific post/page today and if so it'll signal WordPress Popular Posts not to track any repeat visits for the day. The script stores this "viewed" data in localStorage, including the date of the visit.
Please note that this is not a bullet proof solution. Some more savvy users may find a way to work around it so feel free to modify it / improve it as you see fit.