Duplicates in Mac Outlook Calendar

Using Outlook 2011 for Mac... My computer had problems, and I had to reinstall Office from Time Machine. It all came back, except Outlook calendar now displays duplicates of almost every calendar entry. "Almost" is a problem. On the left are two check boxes, that I'd never seen before the reinstall: Calendar, and Calendar (Outlook for Mac Archives). Under each are checked categories (Confirmed, Friends, Fun/family, etc.). I uncheck one, and some entries disappear. Uncheck the other, and other entries disappear. Is my calendar history destined to display two of everything for eternity? Thanks. Tom in Texas