How to Combine Libraries
Wow, after this post went up, a LOT of you wrote to me asking how to combine libraries! There really isn't a straightforward or easy way to combine libraries, but with a little work it can be done. So, by popular request, I'll give you a quick tutorial.
First, you'll need to export a list of EANs to a text file. Select 'Export > To another application' from the 'File' option in the menu bar. From the Export panel that pops up, choose 'Delimited Text' and check 'E.A.N.' from the list of things to export (ASIN should also work, but make sure you only check one or the other. Do not check both!) Hit the 'Export...' button and you should get a text file that is just all your EANs in a list.
You'll need to rename that file 'Scanned UPCs Log.txt'. Make sure it has exactly that title. Once you have this text file with all your EANs in a list in it, transfer it to the other computer using e-mail, Dropbox, etc. Launch Delicious Library 2 on the second machine, and then drag the text file directly onto the library shelves of Delicious Library 2 on that machine. Those EANs should be looked up and the corresponding items added to the second library. You might have to select them and hit 'command-R' to refresh the details from Amazon.
Once you have imported the items, you can delete the file from your computer.
Like I said, this isn't the most intuitive solution, but it should work.