Adding existing images to gallery

I have problem with adding images, that I already uploaded to page, in post that I added. So, images are in gallery on page but I want to add them also in post. When I select images (that I already uploaded to gallery on page) from media library and create gallery they don’t show in post. So, I need to upload same images two times to use them in two galleries like on older version of wordpress. I’m using 3.5 version of wordpress.