Aperture and iPhoto Libraries have identical file formats. You should have the most recent versions of each, and you should not import from one Library into another. Did you, in fact, import your old "photos" from iPhoto into Aperture? How?
Once you get this straightened out, you should simply import into your Library. While it is recommended to use one program or the other -- and if you are settling on Aperture, you should stick with it -- it doesn't matter much which program you use when you import files.
Here are a couple of Apple articles that may be of help:
Thanks. I saw a similar response to another question, so I looked into those articles you referenced. They are talking about iPhoto 11 Version 9.3. Here's the thing...I am running iPhoto 11 Version 9.2.3. When I click on Updates, it says this is the current version. I'm guessing that's why they are not unified.