How to delete user from mention list after mention them for duplicate case like zalo,fb?

[quocviet1996]

I wanna ask like fb, when user A is mentioned, then we can't mention duplicate A. So how to implement such a function? Thanks
I'm trying to delete user mention has been chosen on onSearchChanged, but after that an user mention before has been remove from markup too. You can see this in my attach image

     onSearchChanged:
                                  (String trigger, String value) {
                                if (trigger == "@") {
                                  if (_debounce?.isActive ?? false)
                                    _debounce!.cancel();
                                  _debounce = Timer(
                                      const Duration(milliseconds: 200),
                                      () {
                                    setState(() {
                                      mentiondata.clear();

                                      final List<Map<String, dynamic>>
                                          mentionTemp = [];
                                      mentionTemp.addAll([
                                        {
                                          "id": "3",
                                          "display": "fayeedP",
                                          "photo":
                                              "https://images.pexels.com/photos/220453/pexels-photo-220453.jpeg"
                                        },
                                        {
                                          "id": "5",
                                          "display": "khaled",
                                          "photo":
                                              "https://images.pexels.com/photos/220453/pexels-photo-220453.jpeg",
                                        },
                                      ]);
                                      String text = _bloc.key.currentState!
                                          .controller!.markupText;
                                      RegExp regex = RegExp(
                                          r"@\[\__([a-zA-Z0-9]+)__\]");

                                      Iterable<Match> matches =
                                          regex.allMatches(text);
                                      List<String> results = [];

                                      for (Match match in matches) {
                                        results.add(match.group(1)!);
                                      }
                                      results.forEach((item) {
                                        mentionTemp.removeWhere((element) =>
                                            element['id'] == item);
                                      });
                                      mentiondata = mentionTemp;
                                    });
                                  });
                                }
                              },