If desired, you can copy information from your old second drive onto the new drive. For example, if you are replacing two 10 gig drives with a single 40 gig drive (intending to discard or sell both of the 10s and use only the 40), then you can copy the FIDs from both of the 10 gig drives onto the 40 and it will work. As long as the two 10 gig drives came from the same player, there should not be any file conflicts because the FIDs are designed to be unique within each player's database. This won't work to combine the music from a different player, though.