Imported photos and got duplicate "original" pictures

Question

I have been reading the forum most of the night and decided that at least I could not find a post that was specific to my issue, please forgive if this is redundant.
I have a new mac like many people and am run iphoto 7.x. created a new photo library the first day I plugged in the new machine. I then connected to my ext HDD where I keep the folders of photos from my old mac. These are the folder and files themselves and not the whole iphoto DB file mentioned in other posts (at least as I understand). I then imported the photos through iphoto to the new library.
The issue I have is that often but not always following the import, I now have one copy of many photos for a given day -- e.g group titled 26 which has 6 photos from Aug 26 2007, and then another copy called Originals from Aug 26 too. The originals group has fewer photos than the other (ie. 26 group) and as I said, not every day has this case.
So the question is why did the import create two groups and copies of the picture? Which pictures can be deleted safely? I do not mind deleting by hand but I do not want to get a week down the road and find out that I should have deleted the other set. The effect is similar to what others have seen -- I went from 7000 pics to 10000 due to the extra copies?

Answer 1

Thanks for the reply and the direction to '08 forum -- my next step should be to learn more about the product. I must have overlooked the category title when I posted. My error.
On your directions -- I actually was archiving the folder structure, from Finder, of my old iphoto '06 onto my backup external HDD and not the 'library' database. I would do a fresh backup but the folder based backup was my approach for about a year now and the current version of that '06 library now has only some of the total photos that I want in my new library -- i.e. I have deleted the old archived picture files. Basically this approach was to deal with limited space on my powerbook (common issue with photos I see from the postings).
Can you recommend how best to accurately bring in photos from the folder structure archive. I am not concerned with the reference data -- rating, captions, etc, I just do not want to duplicate the photos given the mass of space that the extra copies take up. In the end I am cool with manually removing the extras but I just can't figure out which copy to delete or if it matters?
TRP