Settings>Backup. Email to your second device - there are instructions within the email (basically, tap on the backup and any playlists listed to import).
If there are songs or playlists on the second device already, you can email those to the first device before importing the backup (otherwise when it imports, you might not be able to find them easily to send). Or to have them completely in sync, make sure there are no songs/playlists you want to retain on the second one, Settings>Erase all, then import the backup from the first.
Keep your email backups for safety
Support information here:
http://irealpro.com/support/
search under Backup
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