diff --git a/app/coffee/modules/common/lightboxes.coffee b/app/coffee/modules/common/lightboxes.coffee
index 38724a29..c3b50b00 100644
--- a/app/coffee/modules/common/lightboxes.coffee
+++ b/app/coffee/modules/common/lightboxes.coffee
@@ -954,9 +954,12 @@ $confirm, $q, attachmentsService, $template, $compile) ->
                 lightboxService.close($el)
                 $rootScope.$broadcast("#{$scope.objType}form:add:success", item)
 
-        $scope.isDisabledExisting = (item) ->
+        isDisabledExisting = (item) ->
             return item && item[$scope.relatedField] == $scope.relatedObjectId
 
+        $scope.isDisabledExisting = (selectedItem) ->
+            isDisabledExisting(selectedItem)
+
         $scope.addExisting = (selectedItem) ->
             event.preventDefault()
             addExisting(selectedItem)
diff --git a/app/partials/common/lightbox/lightbox-create-edit/lb-create-edit.jade b/app/partials/common/lightbox/lightbox-create-edit/lb-create-edit.jade
index a685ea2a..ae22e222 100644
--- a/app/partials/common/lightbox/lightbox-create-edit/lb-create-edit.jade
+++ b/app/partials/common/lightbox/lightbox-create-edit/lb-create-edit.jade
@@ -44,7 +44,7 @@ form(ng-if="lightboxOpen")
 
         button.button-green.add-existing-button(
             ng-click="addExisting(selectedItem)"
-            ng-disabled="!selectedItem"
+            ng-disabled="!selectedItem || isDisabledExisting(selectedItem)"
         ) {{ 'COMMON.ADD' | translate }} {{ objName }}
 
     div(ng-if="mode != 'add-existing'")