tempvar: bug fix for duplicate template var

and a fix for when selecting the same value twice in
a template variable if it is not multi select. It threw an
exception on the second selection

public/app/core/directives/value_select_dropdown.js

@@ -122,7 +122,7 @@ function (angular, _, coreModule) {
     vm.selectValue = function(option, event, commitChange, excludeOthers) {
       if (!option) { return; }
 
-      option.selected = !option.selected;
+      option.selected = vm.variable.multi ? !option.selected: true;
 
       commitChange = commitChange || false;
       excludeOthers = excludeOthers || false;

public/app/features/templating/editor_ctrl.ts

@@ -106,7 +106,7 @@ export class VariableEditorCtrl {
       var clone = _.cloneDeep(variable.getSaveModel());
       $scope.current = variableSrv.createVariableFromModel(clone);
       $scope.current.name = 'copy_of_'+variable.name;
-      $scope.variableSrv.addVariable($scope.current);
+      variableSrv.addVariable($scope.current);
     };
 
     $scope.update = function() {