In the case of Sunny, Rangpur Riders' left-arm spinner, one delivery, the first ball of the 19th over in Rangpur's match against Rajshahi Kings on November 28, raised suspicion.
Video footage of Khulna Titan's allrounder Cooper's bowling has been sent to the WICB, the BPL technical committee chairman Jalal Yunus said.
"Sunny was reported once, in their last game [on November 28]," Yunus said. "The next step would be for the BCB's bowling action review committee to analyse video footage of the delivery, which we will do soon after the end of the tournament. We have sent Cooper's footage to the WICB."
Sunny was suspended for an illegal action during this year's World T20 in March but cleared to bowl by the ICC in international cricket on September 23.
After Sunny and Taskin Ahmed were suspended by the ICC, the BCB formed a bowling action review committee which found five bowlers to have illegal bowling actions during last season's Dhaka Premier League.
Yunus, who is also the chairman of the bowling action review committee, said that they will be stricter on suspected bowling actions.
West Indies' Cooper, too, was reported for a suspected bowling action during this year's Pakistan Super League. Yunus said the BPL wanted to cases such as Cooper's in future.
"In the next BPL, we hope to do the video analysis of suspected bowling action during the tournament itself," Yunus said. "We will also have to be aware of foreign players who has been reported previously, so that we can inform our franchises beforehand. We don't want to have such bowlers in future tournaments."
Mohammad Isam is ESPNcricinfo's Bangladesh correspondent. @isam84