They are both installed by the Canoscan driver for your scanner. However, you don't need both, but they install them anyway. Stupid Canon programmers. The N067U is a LIDE 20 or N670U and the N124U is for the LIDE 30 or N1240U.
They are installed in you Login Items in the Accounts System Prefs.
You should go into you Account prefs and delete the one that is not used as it continually fills your log files with drivel about not finding the scanner that you don't own, but Canon installed the driver anyway. Just open Accounts, select your account, click on Login Items tab, select the unused button manager, and click the delete ( - ) button.