You can select 2 (and only 2 at a time) duplicates the Place View and Merge them from the Toolbar or Edit menu. All the Events set to either Place will be set to the surviving Place.
If you have multiple duplicate entries, you can merge them simultaneously using the Multimerge Addon Gramplet from Isotammi. (If there are multiple Places with identical names, it has an automatic merge for the Place list. It is for consolidating GEDCOM imports that can create many identical duplicate Places.)