Lightbox Image Loading twice and Skipping Images

Hi There,

I have the following website:

http://rugbyfivesassociation.net/gallery/#prettyPhoto

What i am finding is if you click on the second image along when it opens using lightbox it opens the images twice, it only happens on a few images.

Also when clicking through the images the ones which open twice seem to get skipped when scrolling through the gallery.

If someone could help please

T

https://wordpress.org/plugins/nextgen-gallery/