just let me add here that the behaviour of squarespace adding existing images that have already been uploaded is not acceptable and should be addressed by squarespace asap.
we ran into this on a huge site with multiple galleries and hundreds of images and it is a pain working like this. we are spending hours clicking images into an gallery ONE BY ONE! to bad we cant change the plattform at this point. i would if i could ...
there is more when dealing with images:
can't delete images
images that are not used on any page still don't get deleted automatically after 30 days as stated in the documentation (as a result we have a huge pile of images we don't need anymore getting in our way in the daily work)
images in the add-images-dialogue are not sortable
i can't see which images are used on which page - or if they are being referenced at all
different images can have same names
i can't sort images into subfolders
ADVISE: if your site is going to be using lots of images squarespace might not be the best choice for your project.
i contacted support several times about the above issues but besides being super-friendly they can't help.
