Also, I wanted to mention my intent of going back and looking at my 1 and 0 starred photos and taking a moment to really consider if I 'need' those photos - all too often I find myself wanting to keep multiple versions of the same shot (vertical, horizontal, in close, far away) 'just in case' I'll want that orientation, etc.
I know that is kind of silly, as it always magically works out, no matter what, so I should be more comfortable just keeping the photos that I enjoy vs. all the extras shots as 'back-ups'.
I think a key component of this system is something Stacy mentioned - regularly spending time with your photos. In the past I didn't enjoy working with my photos - so many steps and decisions to made then there was photo processing and ordering - argh!
Now, I am seeing how much a difference it makes to spend time in your photo manager when you aren't uploading, editing, or ordering prints; it gives you a chance to enjoy your photos, familiarize yourself with what is there, and with what stories you are excited to tell (i.e. if you aren't excited by a photo, or to tell a story, maybe it shouldn't be a 2 star).
Ok, enough rambling for now!
I definitely understand where you're coming from in wanting to delete duplicates, but want to give one suggestion: Be sure to keep at least one shot that shows context (if you have it) - the room or a car or other people in the background. Things you might be tempted to crop out now can become really interesting and/or important details years down the road.