HOW TO REMOVE COUNTERFEIT WARNING
If you want to remove the annoying counterfeit message that appears in the plugins page, it's pretty simple.
The message itself is actually injected in the update transient, but you can disable it by commenting out line 219 in (all-in-one-wp-migration/lib/controller/class-ai1wm-main-controller.php) of the All-in-One WP Migration core plugin.
JUST CHANGE:
add_action( "in_plugin_update_message-{$extension['basename']}", 'Ai1wm_Updater_Controller::in_plugin_update_message', 10, 2 );
TO:
#add_action( "in_plugin_update_message-{$extension['basename']}", 'Ai1wm_Updater_Controller::in_plugin_update_message', 10, 2 );