Once iTunes downloads track info for a store-bought audio CD, OS X pretends that it is the real directory info for the disc. To make a true duplicate of the CD at this point (i.e. with the proper generic file names), you have to hide the CDDB info, as follows:
- Eject the CD (if inserted)
- Open iTunes Preferences
- Click on Advanced, and then Importing
- Uncheck "Automatically retrieve CD track names from Internet"
- Quit iTunes
- In your home folder, open Library » Preferences
- Rename "CD Info.cidb" to "CD Info.cidb.bak" or similar
- Re-insert the CD
The CD will now show up with the true track names, and iTunes will not go online to replace them. Do whatever you need with the CD in this state. When done, quit iTunes if it has opened, then rename the CD Info.cidb file back to its original name.
Note that until you restore the CD Info.cidb file, all CDs that you insert will show up with generic track names. Also remember to switch your iTunes importing preferences back to normal.