diff --git a/system/project.py b/system/project.py
index f83c093..1b879d0 100644
--- a/system/project.py
+++ b/system/project.py
@@ -21,6 +21,7 @@ class Project:
         self.datasets = []
         self.sel_obj = dataset.Selection('Current Selection')
         self.selections = []
+        self._last_selection = None
         
     def add_selection_observer(self, observer):
         self._selection_observers.append(observer)
@@ -42,8 +43,10 @@ class Project:
         
     def set_selection(self, dim_name, selection):
         """Sets a current selection and notify observers"""
-        self.sel_obj[dim_name] = set(selection)
-        self.notify_selection_listeners(dim_name)
+        if self._last_selection != selection: 
+            self.sel_obj[dim_name] = set(selection)
+            self.notify_selection_listeners(dim_name)
+            self._last_selection = selection
 
     def get_selection(self):
         """Returns the current selection object"""