I created a pdf for https://github.com/mozilla/pdf.js/pull/14023:
[same_fields(1).pdf](https://github.com/mozilla/pdf.js/files/7168340/same_fields.1.pdf)
The 3 checkboxes have the same name (`Check Box2`) and have the same values (`Off` and `Yes`).
In pdf.js, these checkboxes behave like radio buttons in the same group (which is wrong) because of:
https://github.com/mozilla/pdf.js/commit/1fcffe80349a98378262c8a16f7b50ff34c3fe82
Since they've the same values they must be synced: if one is checked (resp. unchecked) then all others are checked (resp. unchecked).
if (!event.target.multiple) {
        return options.selectedIndex === -1
          ? null
          : options[options.selectedIndex][name];
      }
      return Array.prototype.filter
        .call(options, option => option.selected)
        .map(option => option[name]);
    };
    const getItems = event => {
      const options = event.target.options;
      return Array.prototype.map.call(options, option => {
        return { displayValue: option.textContent, exportValue: option.value };
      });
    };
    if (this.enableScripting && this.hasJSActions) {
      selectElement.addEventListener("updatefromsandbox", jsEvent => {
        const actions = {
          value(event) {
            const options = selectElement.options;
            const value = event.detail.value;
            const values = new Set(Array.isArray(value) ? value : [value]);
            Array.prototype.forEach.call(options, option => {
              option.selected = values.has(option.value);
            });
            storage.setValue(id, {
              value: getValue(event,  true),
            });
          },
          multipleSelection(event) {