Hello I would like to say that transmission of HIV depend on many conditions , as in this case IF any boy ( among two ) was an HIV infected then there is chance of getting HIV infection is much more . If among two NO body was any HIV infected no chance of getting infection. Further this is also important ,that if one or two were an HIV infected , the risk increases for exposure to sex the higher from a patient with advanced-stage disease , if presence of more virulent strains of virus , antiviral treatment by boys or boy if some one was infected, because in this case both boys ejaculated in vagina. If the girl have any stress or doubt get in rapid P 24 pcr , rna rapid nucleic acid amplification test for HIV confirmation after 2 weeks of initial infection ( contract with boys). Hope this will help you.