Auto import only has the one folder. Good. The symlink is what's causing the confusion, but you probably knew that, which is why you told us.
Take a look at the location for your ripped files:
Tools > Options > File Location > Audio (CD rips and podcasts)
It's probably set to ~/Music with a subdirectory. So, when you rip, it puts the files there and imports them. But auto import is looking at the "real" directory in /Data/... , so it imports the files *again*.
The solution is either to change the rip location to /Data/Steve... , or to remove the symlink. Or to rip with another application.
In the mean time, you can easily delete all of the duplicates. Use the Files view and drill down by location to ~/Music . Or do a search for /Users/Steve/Music (or whatever the full path is). Once you have the list of files, just choose delete and tell it to remove from Library only. Do NOT remove from disk. That should leave you with only one copy of each.
Brian.