A deliberate move
The left bower is shown with trump because that is its effective suit for the hand. It is not duplicated in the other suit’s list.
Check the whole display
The diagram still accounts for all twenty-four cards. One suit has gained a jack while another has lost it. Switch the trump selector and watch which jack changes groups.
Use a complete rule when playing
This visual aid explains the grouping. It does not inspect your hand or decide the winner of an arbitrary trick. Follow the linked reference for the full legal-play conditions.