SALEM – She was scheduled to plead guilty Friday to charges of raping a 15-year-old boy, but a Saugus mother now faces an August trial on those and a second set of child-rape charges involving the boy’s twin brother.”My client was prepared to take responsibility for the first set of indictments ? we completely, uncategorically deny anything happened with the second individual,” Defense Attorney William Korman said outside the courtroom Tuesday morning.”We wonder what motivated this second disclosure, and we have some real concerns about the validity of these disclosures.”Heather Salines, 39, pleaded not guilty in Salem Superior Court in June 2014 to six counts of aggravated child rape; and single counts each of enticement of a child; and distributing obscene matter to a child.Salines returned to the courtroom Tuesday to plead not guilty to aggravated child rape; indecent assault and battery on a person 14 years or older; child enticement; and disseminating harmful material to a minor.The first set of charges concern allegations that Salines had sex with a boy in March 2014 who was 15 at the time and a friend of Salines’ daughter. Salines told police that “she developed feelings that she was not proud of” and had sex with the alleged victim in her car and in a hotel room, police said. Salines also said she and the boy exchanged nude pictures, according to court documents.Prosecutors called the boy “vulnerable” because his own mother had died and he saw Salines as a “mother figure.”The second set of charges predate the initial complaint; referencing an alleged incident in February 2014 when the alleged victim – the twin brother of the first alleged victim – was 14.Essex Assistant District Attorney Kate MacDougall did not present any details of the allegations in open court nor request that she further bail than the $7,500 Salines posted after her arraignment on the first charges in Salem District Court. She only acknowledged the two victims were twin brothers after Judge John Lu refused her request – and the request of Korman – that the attorneys meet the judge at sidebar.”There’s apparently great public interest in this case,” Lu said in refusing the request.Essex District Attorney spokesperson Carrie Kimball-Monahan said in a press release that the second set of charges allege Salines raped the boy in her Saugus home and allegedly sent explicit photos of herself to the child.MacDougall said the cases would likely be joined, and Lu scheduled a trial date of Aug. 17.Both alleged victims were present at the arraignment, and Salines looked at them as she left the courtroom.A woman declined to comment on behalf of the alleged victims.