From A Wiki of Ice and Fire
There have been multiple members of House Targaryen named Gaemon Targaryen:
- Lord Gaemon Targaryen, a Lord of Dragonstone.
- Prince Gaemon Targaryen, a son of King Jaehaerys I and Queen Alysanne Targaryen, died young.
There is also:
- Gaemon Palehair, an alleged bastard son of King Aegon II and a pretender king during the Dance of the Dragons