Unbind the previous handler when a new handler is added

Author: rostilos

app/code/Magento/Wishlist/view/frontend/web/js/add-to-wishlist.js

@@ -225,12 +225,22 @@ define([
             });
         },
 
+        /**
+         * Unbind previous form submit listener.
+         */
+        unbindFormSubmit: function () {
+            $('[data-action="add-to-wishlist"]').off('click');
+        },
+
         /**
          * Bind form submit.
          */
         bindFormSubmit: function () {
             var self = this;
 
+            // Prevents double handlers and duplicate requests to add to Wishlist
+            this.unbindFormSubmit();
+
             $('[data-action="add-to-wishlist"]').on('click', function (event) {
                 var element, params, form, action;