The Reds were the winners of the Ghana Premier League matchday 15 encounters that took place at the Baba Yara Stadium.
Etouga put dominant Kotoko in front from the spot after he was fouled in the area. The Cameroonian stepped up and converted what is his seventh goal of the season.
Kotoko continued to take control of the game with goalkeeper Danlad Ibrahim having less work to do.
The Porcupines double their lead through Mbella who grabbed his brace after connecting Richmond Lamptey’s pass inside the box.
Olympics had two key moments in the first half fell to Maxwell Abbey Quaye but the Black Stars blasted wide on both occasions.
In the second half, Kotoko managed the game and made sure they kept the score intact to bag yet another three points.
Following the win, the league leaders have extended the unbeaten streak to seven, six wins, and a draw.
Asante Kotoko, who are on 33 points have now opened 9 points gap at the top of the table. Whereas Olympics slip to 6th on 22 points.