Don't allow to create the same error messages

src/store/messages.js

@@ -16,6 +16,7 @@
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 import i from 'immutable';
+import { find } from 'lodash';
 import { LOCATION_CHANGE } from 'react-router-redux';
 
 import { messages } from '../actions';
@@ -33,6 +34,13 @@ function removeDuplicate(state, action) {
 }
 
 export default function reducer(state = initialState, action) {
+  if (find([messages.ADD_ERROR, messages.ADD_MESSAGE], a => a === action.type)) {
+    const index = state.findIndex(item => item.message === action.message);
+    if (index !== -1) {
+      state = state.delete(index);
+    }
+  }
+
   switch (action.type) {
     case messages.ADD_ERROR: {
       state = removeDuplicate(state, action);