How our tracking works is it counts only those unique visits to your page.
Third party tracking may be using a different method counting the clicks on your page.
One factor that may be different is that some external tracking counts all of the clicks to your page without filtering if the click came twice from the same visitor. If that's the case, the external tracking may count this click as 2 and our internal tracking will count it as 1.
You may have to check with your external tracking how exactly they record their data, but on our end, the numbers that you see in there are accurately the number of unique clicks to the page.