Ok, this is my theory about why Olver is NOT Gaidal Cain. Back in the beginning of the series when Mat blew the Horn of Valere, Gaidal Cane was there fighting with him at Falme. Since that time only a year or two have passed and Olver is 9 years old which means he was already born and existing in the world when Gaidal was fighting at Falme. I realize the big arguement is that time is different in the world of dreams but he still couldn't have been existing as two people at once.