iPod iTunes, duplicating?

Okay, I need some of your expert advice.

Some years ago, when we got our first iPod Classic (which wasn't classic back then, haha), I spent an ENTIRE weekend swapping out and ripping CD's, one every 10 minutes or so. FOR HOURS!!

Well, do to then-space limitations, we ended up parsing some of those songs and deleting them.

I would like to undergo a repeat project, over the course of a few weeks of course, of re-ripping ALL of my CDs to ensure that ALL of our music is in iTunes.

Will iTunes advise me when a CD is being duplicated so I can save the time it takes ripping that one and allow me to move on to the next?

If not, once I've re-ripped my 2 or 300 CDs, is there a simple way to delete the dupicates out of iTunes? What if they are different versions of the same song - exactly but from different sources (different CDs, like Artist X, then Artist X Greatest Hits, or Artist X as part of a soundtrack compilation).

What if they are different versions such as a live version, or an extended version?

Thanks for your experienced input!

This is very helpful, thank you Consultant.

I don't know which CDs I do or don't have, and my "Due to space limitations" can both be elaborated upon and explained in the same response (Thanks for calling me out on it btw):

I ripped EVERYTHING we had into iTunes back in 2002/3/4/whenever, for a Christmas gift iPod. The recipient of same decided she did not want certain music, even entire CDs and two entire genres, so she deleted them out of iTunes. Partly because she didn't like the music, partly because we didn't know that this would be a permanent platform paradigm shift, and partly because we didn't know how much room we would need for future expansion.

That is why I don't know what is in the iTunes Library exactly, and that is why I didn't elaborate on the "Space limitations" portion of my post.

I will use your advice to better manage my Library, I appreciate you taking the time to respond- you're the only one that has so far.