Wordpress - add_menu_page() with different name for first submenu item

You can make the 'slug' for the submenu page equal that of the top level page, and they'll point to the same place:

add_action('admin_menu', 'my_menu_pages');
function my_menu_pages(){
    add_menu_page('My Page Title', 'My Menu Title', 'manage_options', 'my-menu', 'my_menu_output' );
    add_submenu_page('my-menu', 'Submenu Page Title', 'Whatever You Want', 'manage_options', 'my-menu' );
    add_submenu_page('my-menu', 'Submenu Page Title2', 'Whatever You Want2', 'manage_options', 'my-menu2' );
}

E.g.

make the slug of parent menu item and sub menu same (first one item) like below

function actions_recent_bids_add_admin_page(){

add_menu_page('Recent Bids', 'Auction Reports', 'manage_options','wc-auction-reports','actions_recent_bids_list','dashicons-chart-area', 56);   
  
add_submenu_page(
    'wc-auction-reports',               // parent slug
    'Recent Bids',                      // page title
    'Recent Bids',                      // menu title
    'manage_options',                   // capability
    'wc-auction-reports',               // slug
    'acutions_customers_spendings_list' // callback
); 


add_submenu_page(
    'wc-auction-reports',               // parent slug
    'Customer Spending',                // page title
    'Customer Spending',                // menu title
    'manage_options',                   // capability
    'wc-acutions-customers-spendings',  // slug
    'acutions_customers_spendings_list' // callback
); 
 
add_submenu_page(
    'wc-auction-reports',          // parent slug
    'Customer Bids',               // page title
    'Customer Bids',               // menu title
    'manage_options',              // capability
    'wc-acutions-customers-bids',  // slug
    'acutions_customers_bids_list' // callback
);  

}

add_action('admin_menu','actions_recent_bids_add_admin_page');