Custom reports and the report pages shows different data

I have noticed for the url that ends with /mina-sidor/mina-sidor/ it has around 500 page views for a specifik day if i look in the report under custom report. But if i look in the standard report pages it has around 1 000 pageviews. The custom report i filtered url ends with /mina-sidor/mina-sidor/.

How come it can be such a big difference?