I noticed the folder contents of c\nokia\images AND c\nokia\images_tn are both exactly the same! Are the images stored twice, if so is it ok to delete them... If there not stored twice then why this? I've noticed it on two of my friends devices too [im running 4.36 there on 3.12 and 3.36]

images_tn is for those thumbnail(small) images you see in the image folder.
Those can be deleted, but the phone makes them again, when you look at the photos.