The allegations were made during the second day of the trial of Gemase Lee Simmons, the San Antonio Express News reported Wednesday.
The two girls are among eight listed in an indictment against Simmons, who was charged last year by the FBI with 39 counts related to child pornography, and extortion and bank fraud.
Witnesses testified Tuesday the girls, accompanied by their mothers, went to Simmons' high-end San Antonio apartment for modeling tryouts. Without their mothers' knowledge, Simmons told the girls to email explicit photos and images of themselves to models he recommended.
The "models" were actually Simmons, who prosecutors said used digital applications to disguise the communications.
When the girls requested that their images be destroyed, witnesses said, Simmons told them to send him more or he would publish the photos.
If convicted, Simmons faces 15 years in prison without parole.