One victim was 13, and he attempted to exploit another boy who was aged just 11.
Judge Jane Farish remanded Hore, a data entry operator from Belfast, in custody until he is sentenced at the High Court on July 4.
The Crown withdrew a further 10 charges.
Defence counsel Margaret Sewell said a psychological report was being prepared and Judge Farish called for a pre-sentence report.
Last November, Christchurch police released details of Hore's offending, including the name and photograph of his false female profile, Sarah Ruddenklau.
Officers received around 20 complaints from people who claimed to have been deceived by Hore, including complaints form his own "close family, cousins, friends and associates,'' police said.