Kendo Ui grid Custom Validation is firing twice

问题:

Kendo Ui grid Custom Validation is firing twice

My coding

schema: {
                    model: {
                        id: "StaffID",
                        fields: {
                            StaffName: { validation: { required: true }  },
                            RoleID: { field: "RoleID", type: "number", defaultValue: 2 },
                            Username: { validation: { required: true } },
                            Password: { validation: { required: true } },
                            Email: {
                                validation: {
                                    email: true, required: true,validateOnBlur: false,
                                    EmailValidation: function(input)
                                     **// This is fired twice**
                                   { 
                                        var valid = CheckEmailValidate(input,dataSource,dataItem);
                                        return valid;                                         
                                    }
                                }
                            }
                        }
                    }
                }

Reference: please Check http://demos.telerik.com/kendo-ui/grid/editing