Thanks Andy and Furas for your lights,

Here is the corrected code after:

1. commenting

   1.1) the line #md_bg_color: 0/255, 128/255, 128/255, 1 # teal by default (RGBA)

   1.2) the line #md_bg_color: 0, 0, 1, 1 # blue by default (RGBA)

   Each line was generating a red dot. So in total we have 2 red dots. So it wasn't possible to define the background color of the badges in the KV string. By default, the background color of each badge is red. So the only option was to dynamically define each badge's colour at the start of the code.

2. Adding the event on_start function So I have added the on_start event function to define each color of the background of each badge.

Corrected code: From kivy.lang import Builder from kivymd.app import MDApp

KV = """
MDScreen:
    MDBoxLayout:
        orientation: "vertical"
        MDTopAppBar:
            font_style: "Display"
            role: "small"
            size_hint_x: 1 # This makes sure the top bar spans the full width of the screen
            pos_hint: {"top": 1}  # Ensures the TopAppBar is at the top of the screen
            MDTopAppBarLeadingButtonContainer:
                MDActionTopAppBarButton:
                    icon: "arrow-left"
                    on_release: app.back_to_previous_screen()
            MDTopAppBarTitle:
                id: edit_cards_top_app_title
                text: "Manager App"
            MDTopAppBarTrailingButtonContainer:
                MDActionTopAppBarButton:
                    icon: "file-document-multiple"
                    MDBadge:
                        id: edit_cards_badge_table_rows
                        text: "0"
                        #md_bg_color: 0/255, 128/255, 128/255, 1  # teal by default (RGBA)
                MDActionTopAppBarButton:
                    icon: "database"
                    MDBadge:
                        id: edit_cards_badge_table
                        text: "0"
                        #md_bg_color: 0, 0, 1, 1  # blue by default (RGBA)
        MDScrollView:
            pos_hint_x: 1
            size_hint_y: 1      
            MDList:
                #size_hint_y: None 
                #height: self.minimum_height
                pos_hint_x: 1 #{"center_x": .5}
                id: double_card_list        
                MDBoxLayout:
                    orientation: 'horizontal'
                    size_hint_y: None
                    height: "480dp" # Define the size here for both cards
                    padding: "10dp"  # Define the space outside around the MDCard here
                    spacing: "10dp"  # Define the horizontal space between the cards here
                    # Row1 Card1                  
                    MDCard:
                        size_hint_x: None
                        size_hint_x: "400dp" 
                        elevation: 10
                        radius: [10]
                        MDBoxLayout:
                            orientation: 'vertical'
                            padding: "10dp" # Inside the border of the card
                            spacing: "5dp"
                            MDLabel:
                                text: "Product Information"
                                halign: "center"
                    # Row1 Card2   
                    MDCard:
                        size_hint_x: None
                        size_hint_x: "400dp" 
                        #size_hint_y: None
                        #size_hint_y: "750dp"                        
                        elevation: 10
                        radius: [10]
                        MDBoxLayout:
                            orientation: 'vertical'
                            padding: "10dp" #Inside the border of the card
                            spacing: "5dp"
                            MDLabel:
                                text: "Agency Information"
                                halign: "center"
        MDListItem:
            id: status_bar
            size_hint_y: None
            height: "70dp"
            #md_bg_color: (137/255, 196/255, 244/255, 1)  # Jordy blue background (RGBA) # Do not work
            #size_hint_x: 0.85
            #pos_hint: {"center_x": 0.5}  # Center the status bar
            size_hint_x: 1
            MDListItemHeadlineText:
                text: "Status :"
            MDListItemSupportingText:
                id: status_bar_supporting_text
                text: "Supporting text:"
            MDListItemTertiaryText:
                text: "Tertiary text"
"""
class Example_unexpected_2_red_dots_with_correction(MDApp):
    def build(self):
        return Builder.load_string(KV)
    
    def on_start(self):
        # Customize the color of the badges dynamically at start
        self.root.ids.edit_cards_badge_table_rows.md_bg_color= (0/255, 128/255, 128/255, 1) # RGBA Teal color of the badge changed dynamically at start
        self.root.ids.edit_cards_badge_table.md_bg_color=      (0/255, 0/255, 255/255, 1)   # RGBA Blue color of the badge changed dynamically at start 

Example_unexpected_2_red_dots_with_correction().run()