And police fear Anthony Marsh, 53, and Lee Davis, 39, who have already admitted a string of sex offences, may have had more victims.
The pair used social networks such as Facebook and Bebo, as well as specialist gay websites, to befriend boys before committing what police describe as "vile, horrendous offences".
After grooming the boys online, Marsh, who has HIV, and Davis would meet their victims and abuse them.
The pair admitted a string of sex offences at Sheffield Crown Court last month. Yesterday, prosecutors decided they will not proceed with a small number of allegations denied by the pair.
But detectives believe there may be more victims, who have yet to be traced.
Police said Marsh, of Hatfield, and Davis,of Conisbrough, both South Yorkshire, were family men whose wives were unaware of what they were doing.
Marsh and Davis will be sentenced on December 2.