只需使用php、html和vanila js，就可以将TimeZone放入两个选择标记中

<select id="timezone1"></select>
<select id="timezone2"></select>

// 获取时区数据
var timezones = <?php echo json_encode(DateTimeZone::listIdentifiers()); ?>;

// 填充选择标记
var select1 = document.getElementById("timezone1");
var select2 = document.getElementById("timezone2");

timezones.forEach(function(timezone) {
  var option1 = document.createElement("option");
  option1.text = timezone;
  option1.value = timezone;
  select1.add(option1);

  var option2 = document.createElement("option");
  option2.text = timezone;
  option2.value = timezone;
  select2.add(option2);
});

select1.addEventListener("change", function() {
  var selectedTimezone1 = select1.value;
  console.log("选择的时区1：" + selectedTimezone1);
});

select2.addEventListener("change", function() {
  var selectedTimezone2 = select2.value;
  console.log("选择的时区2：" + selectedTimezone2);
});