If I have 2 {captivating vampires} in play do they give each other bonuses
Yes they will. If it said "all Vampires not named Captivating Vampire get +1/+1" it would be different. It only excludes the card itself; having two would give them both the bonus.
RESOLVED
Thanks I had an opponent tell me they don't give each other bonuses
Opponents will try and tell you things. Do not trust what is not written.