Midfielder Britto, who wore the number seven shirt in the first half of Wednesday's Paulista (Sao Paulo state) championship match, returned from the halftime break with the number five, the same as defender Rafael Silva.
The referee only noticed the ruse 26 minutes later when he ordered Britto to change his shirt and gave him a yellow card.
"They were on the attack and we used all the tricks we could to keep them at bay," Britto, who finished the match wearing number 17, told the Sportv cable channel after Barbarense's 3-2 win. "It was a strategy and it worked."
Former South American champions Palmeiras suffered a humiliating 6-2 defeat at Mirassol with all the goals coming in an incredible first half.
Palmeiras debutant Marcos Vinicius made a nightmare start as he headed into his own goal after only 40 seconds and Mirassol added two more before the 15th minute.
Palmeiras pulled two back only to concede another three in a seven-minute spell before halftime. The result is bound to lead to speculation over the future of coach Gilson Kleina.
Striker Luis Fabiano scored both goals as Sao Paulo won 2-0 at Paulista while world club champions Corinthians were held to a 1-1 draw at home to Penapolense.
Nineteen-year-old striker Michael scored a first-half hat-trick to give Fluminense a 3-1 win over Macae in Rio de Janeiro's Carioca championship.
He opened his account in the 23rd minute by winning possession and slotting the ball past goalkeeper Luis Henrique, then swept home a low cross from Wagner four minutes later.
The teenager completed his hat-trick with an impressive finish after the ball was back-heeled to him on the stroke of halftime.
Vasco da Gama were held to a goalless draw by Olaria in their first match under former Qatar and Peru coach Paulo Autuori.