Hi there, @cpond0723, thanks for reaching out to us!
The Photos tab is the place where all the photos in your account show up, so you'd have to delete the duplicates from your account, for them to be removed from the Photos tab as well.
And as for editing the creation date of your photos, I'm afraid there's no way to edit them through Dropbox.
You'll either need to use the options available in your operating system, or a third-party service/app.
If you have any questions, let us know.