物料选择jQuery函数不适用于显示下拉列表

Question

我已使用materialSelect jquery命令显示下拉框。我已经为2个下拉菜单写了两次，但显示了4次。当我只写一次命令时，一个下拉菜单工作而另一个则没有。有人可以帮我了解一下这是怎么回事。

$("#drop1").ready(function() {
  $(".mdb-select").materialSelect();
});

$("#drop2").ready(function() {
  $(".mdb-select").materialSelect();
});

arr = ["Honda", "Suzuki", "Hyundai"];
var select = document.getElementById("Drop1");
for (var i = 0; i < arr.length; i++) {
  var option = document.createElement("OPTION"),
    txt = document.createTextNode(arr[i]);
  option.appendChild(txt);
  option.setAttribute("value", arr[i]);
  select.insertBefore(option, select.lastChild);
}

var select1 = document.getElementById("Drop2");
for (var i = 0; i < arr.length; i++) {
  var options = document.createElement("OPTION"),
    txt = document.createTextNode(arr[i]);
  options.appendChild(txt);
  options.setAttribute("value", arr[i]);
  select1.insertBefore(options, select1.lastChild);
}

<div class="col-3">
  <select id="Drop1" class="mdb-select md-form colorful-select dropdown-dark mx-2" multiple>
    <option value="" disabled selected>Car Features</option>
  </select>
  <label class="mdb-main-label">Car Features</label>
</div>

<div class="col-3">
  <select id="Drop2" class="mdb-select md-form colorful-select dropdown-dark mx-2" multiple>
    <option value="" disabled selected>Bike Features</option>
  </select>
  <label class="mdb-main-label">Bike Features</label>
</div>