In previous versions of windows i was able to select all the photos i wanted imported from my phone, but i had the option to not import the ones that have already been imported. I like backing up my photos to my computer from time to time. I don't want duplicates of all my photos, but i also don't want to have to individually select each photo i want to import. Is there a way i could still select all but not have previously imported photos be imported again with windows 8?

This depends on the settings on the phone. This issue might have caused due to any settings issue in the import settings. I would suggest you to try the steps provided in the following Microsoft Help article and check if it helps.

How do I import photos and videos from a camera, phone, or DVD?

http://windows.microsoft.com/en-us/windows-8/import-photos-videos

For further reference, you may refer to the following Microsoft Help article.

http://windows.microsoft.com/en-us/windows-8/photos-app-faq