how to not select multiple item in group with dropdown select2dot1 at flutter

I only want to take nameSingleItem from one nameCategory? so for example there are 10 nameCategories and each of them has a nameSingleItem with the item of the nameSingleItem is the same. so focus on items from one nameCategory.

static const List<SingleCategoryModel> campOptions = [
    SingleCategoryModel(
      nameCategory: 'Camp Nomor 15',
      singleItemCategoryList: [
        SingleItemCategoryModel(nameSingleItem: "VVIP"),
        SingleItemCategoryModel(nameSingleItem: 'VIP'),
        SingleItemCategoryModel(nameSingleItem: 'Barrack'),
      ],
    ),
    SingleCategoryModel(
      nameCategory: 'Camp Nomor 16',
      singleItemCategoryList: [
        SingleItemCategoryModel(nameSingleItem: 'VIP'),
        SingleItemCategoryModel(nameSingleItem: 'Barrack'),
      ],
    ),
  ];

          SizedBox(
            width: 300,
            child: Select2dot1(
              selectDataController: SelectDataController(
                data: campOptions,
                isMultiSelect: false, //false for pick 1 item, while true for pick multiple
              ),
              pillboxTitleSettings: const PillboxTitleSettings(
                title: 'Pilih Tipe Camp',
                titleStyleDefault: TextStyle(
                  fontSize: 16,
                  fontWeight: FontWeight.bold,
                  color: Colors.black,
                ),
              ),
              pillboxSettings: PillboxSettings(
                defaultDecoration: BoxDecoration(
                  border: Border.all(color: Colors.black, width: 1.5),
                  borderRadius: BorderRadius.circular(8),
                  color: Colors.white,
                ),
              ),
              onChanged: (selectedItems) {
                if (selectedItems.isNotEmpty) {
                  final selectedItem = selectedItems.first;
                  print("Tipe Camp Terpilih: ${selectedItem.nameSingleItem}");
                }
              },
            ),
          ),

You can add a value after nameSingleItem with an example

SingleItemCategoryModel(nameSingleItem: "VVIP", value '15-1')
//example value:15-1. 15 is the camp id, 1 is the room type id