The script works twice, how to fix it?

Question

JavaScript

Hello. It costs opencart 3.0.3.3, when you click on the plus or minus button in the product, the product in quantity is displayed in increments of 2, that is, 2,4,6,8, etc. For some reason, the script works twice. Please help me figure out what the problem is. I am attaching the code. A link to an example of a product is also https://edelveystex.ru/zhenskij-trikotazh/halaty/h...

/* Quantity plus minus - Product Detail
 ========================================================*/
$(function ($) {
    "use strict";
    $.initQuantity = function ($control) {
        $control.each(function () {
            var $this = $(this),
                data = $this.data("inited-control"),
                $plus = $(".input-group-addon:last", $this),
                $minus = $(".input-group-addon:first", $this),
                $value = $(".form-control", $this);
            if (!data) {
                $control.attr("unselectable", "on").css({
                    "-moz-user-select": "none",
                    "-o-user-select": "none",
                    "-khtml-user-select": "none",
                    "-webkit-user-select": "none",
                    "-ms-user-select": "none",
                    "user-select": "none"
                }).bind("selectstart", function () {
                    return false
                });
                $plus.click(function () {
                    console.log($value.val())
                    if (!$($value).is('.size-quantity:disabled') && !($($value).is('.main-quantity') && $('.all-sizes:checked').length == 0)) {
                        var val = parseInt($value.val()) + 1;
                        $value.val(val);

                        if ($($value).is('.main-quantity') && $('.all-sizes:checked').length > 0) {
                            $('.size-quantity').val($($value).val());
                        }

                        if ($($value).is('.size-quantity') && $('.all-sizes:checked').length === 0) {
                            $('.main-quantity').val($.map($('.size-quantity'),(s)=> parseInt($(s).val())).reduce((c,b)=> c+b,0));
                        }
                        getProductSummary();
                    }
                    return false
                });
                $minus.click(function () {
                    if (!$($value).is('.size-quantity:disabled') && !($($value).is('.main-quantity') && $('.all-sizes:checked').length == 0)) {
                        var val = parseInt($value.val()) - 1;
                        $value.val(val > -1 ? val : 0);
                        if ($($value).is('.main-quantity') && $('.all-sizes:checked').length > 0) {
                            $('.size-quantity').val($($value).val());
                        }

                        if ($($value).is('.size-quantity') && $('.all-sizes:checked').length === 0) {
                            $('.main-quantity').val($.map($('.size-quantity'),(s)=> parseInt($(s).val())).reduce((c,b)=> c+b,0));
                        }
                        getProductSummary();
                    }
                    return false
                });
                $value.blur(function () {
                    if (!$($value).is('.size-quantity:disabled') && !($($value).is('.main-quantity') && $('.all-sizes:checked').length == 0)) {
                        var val = parseInt($value.val());
                        $value.val(val > -1 ? val : 0);
                        if ($($value).is('.main-quantity') && $('.all-sizes:checked').length > 0) {
                            $('.size-quantity').val($($value).val());
                        }

                        if ($($value).is('.size-quantity') && $('.all-sizes:checked').length === 0) {
                            $('.main-quantity').val($.map($('.size-quantity'),(s)=> parseInt($(s).val())).reduce((c,b)=> c+b,0));
                        }
                        getProductSummary();
                    }
                })
            }
        })
    };
    $.initQuantity($(".quantity-control"));
    $.initSelect = function ($select) {
        $select.each(function () {
            var $this = $(this),
                data = $this.data("inited-select"),
                $value = $(".value", $this),
                $hidden = $(".input-hidden", $this),
                $items = $(".dropdown-menu li > a", $this);
            if (!data) {
                $items.click(function (e) {
                    if ($(this).closest(".sort-isotope").length >
                        0) e.preventDefault();
                    var data = $(this).attr("data-value"),
                        dataHTML = $(this).html();
                    $this.trigger("change", {
                        value: data,
                        html: dataHTML
                    });
                    $value.html(dataHTML);
                    if ($hidden.length) $hidden.val(data)
                });
                $this.data("inited-select", true)
            }
        })
    };
    $.initSelect($(".btn-select"))
});

Answer 1

Connect scripts in a single amount to the page.

Answer 2

Arseniy Matytsin can you explain in more detail, please