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).
while (selectElement.length !== 0) {
              selectElement.remove(0);
            }
            storage.setValue(id, { value: null, items: [] });
          },
          insert(event) {
            const { index, displayValue, exportValue } = event.detail.insert;
            const optionElement = document.createElement("option");
            optionElement.textContent = displayValue;
            optionElement.value = exportValue;
            selectElement.insertBefore(
              optionElement,
              selectElement.children[index]
            );
            storage.setValue(id, {
              value: getValue(event,  true),
              items: getItems(event),
            });
          },
          items(event) {