Some galleries or plugins add images including the links to the media files twice for lazy loading. This causes PhotoSwipe to show the images twice as well.
The frontend script should use each image only once. Before an image is added to the lightbox collection, it should check if there is already an entry for the same URL.
Also see here: https://wordpress.org/support/topic/gallery-repeats-twice-in-lightbox/
Some galleries or plugins add images including the links to the media files twice for lazy loading. This causes PhotoSwipe to show the images twice as well.
The frontend script should use each image only once. Before an image is added to the lightbox collection, it should check if there is already an entry for the same URL.