I know that there is an import tool to port RS1 songs into RS2014, but has anyone installed both programs on the same computer and run them individually?  Are the songs on RS1 completely different or are the several duplicates?

You can, but I don't understand what you mean by "duplicates". The basic song list is different on both games.

Each game has its own basic set of songs. There are no duplicate songs. You'll find the setlists on wikipedia for Rocksmith and Rocksmith 2014. If you spend 10,- € you can buy the disc importer tool for Rocksmith 2014 which will import all Songs of Rocksmith if you own both programs.

Yes, I have both RS and RS2014 on the same computer. I have the import tool so RS songs appear in RS2014, I can not play RS2014 songs in RS.

Thanks for all the info!

Yes, I have both RS and RS2014 on the same computer. I have the import tool so RS songs appear in RS2014, I can not play RS2014 songs in RS.

nor will you be able to as they are different file types.