My b2evolution Version: 2.x
I decided to install a second blog on my site, a photo blog for my project 365 photos. Currently all my project 365 posts are on my main blog in their own category. I moved the category from the main blog to the photoblog. The posts all show up fine on the photoblog but they are also still on the main blog. I was assuming (incorrectly it seems) that moving the category would remove the posts from the main blog. I tried unpublishing a post from the main blog and that unpublishes it from the photoblog as well.
Have I done something wrong or is this how it works when you move categories? I would really like to strip the posts from the main blog and have them only on the photoblog BUT I don't want to have to do this post by post. (I'm lazy) :p
Seems like your posts linked in both categories now. Edit any post (make sure to edit /conf/_admin.php to allow crossposting) and see if it has 2 categories. You may need to edit all posts one by one or try to remove the original category.
If the above is not true you might have one blog aggregating another. Check the settings for original blog where you moved the posts from.