Angularjs custom form control scope is duplicated

I have created a simple angularjs directive to input city and zip codes. It works fine except that if I used it twice within the same controller the values in the input field are duplicated! I believe it's a scope problem but I don't know how to solve it?

FDVilleModule = angular.module('FDVille', []).
  directive('fdVille', () ->
    return {
      restrict: 'E'
      require: 'ngModel'

      template: """                                                                                                                                                                                                                                                             
        <div class=\"row-fluid\">                                                                                                                                                                                                                                               
          <div class=\"span4\">                                                                                                                                                                                                                                                 
            <input                                                                                                                                                                                                                                                              
              ng-model=\"cp\"                                                                                                                                                                                                                                                   
              ng-change=\"edit()\"                                                                                                                                                                                                                                              
              maxlength=\"5\"                                                                                                                                                                                                                                                   
              type=\"text\"                                                                                                                                                                                                                                                     
              class=\"input-block-level\"                                                                                                                                                                                                                                       
              placeholder=\"Code Postal\" />                                                                                                                                                                                                                                    
          </div>                                                                                                                                                                                                                                                                
          <div class=\"span8\">                                                                                                                                                                                                                                                 
            <select ng-model=\"selected_ville\"                                                                                                                                                                                                                                 
              ng-options=\"v.id as v.nom for v in villes\"                                                                                                                                                                                                                      
              class=\"input-block-level\">                                                                                                                                                                                                                                      
            </select>                                                                                                                                                                                                                                                           
          </div>                                                                                                                                                                                                                                                                
        </div>"""

      link: (scope, elem, attr, ctrl) ->
        scope.$watch('selected_ville', (value)->
          ctrl.$setViewValue(value))

      controller: ($scope) ->
        download_villes = (cp) -> $.getJSON('/ws/villes/cp', {cp:cp}, set_data)
        download_villesid = (id) -> $.getJSON('/ws/villes/id', {id:id}, set_init_data)

        set_data = (results) ->
          $scope.villes = results
          $scope.selected_ville = results[0].id if results.length
          $scope.$apply()

        saved_cp = ""
        $scope.edit = () ->
          if isNaN($scope.cp)
            $scope.cp = saved_cp
          else
            saved_cp = $scope.cp
            if saved_cp.length == 5
              download_villes(saved_cp)
            else
              $scope.selected_ville = null
              $scope.villes = []
    }
  )

Actually I found the answer in the docs:

scope - If set to:

true - then a new scope will be created for this directive. If multiple directives on the same element request a new scope, only one new scope is created. The new scope rule does not apply for the root of the template since the root of the template always gets a new scope.

In some other instance, you could try

replace: true

Note: you need to have one root element.

Here's the link to the documentation for us readers who didn't know:

http://docs.angularjs.org/guide/directive