Yes, there are more than sixty-seven kalashtar. There are also more than sixty-six, since the kalashtar bound to their leader, Taratai, sacrificed themselves to produce the shroud resonators that protect Adar (Secrets of Sarlona, pg. 24).
Sixty-seven rebel quori survived the exodus from Dal Quor, and every kalashtar has a bond to one of these spirits. The suffix attached to a kalashtar’s name is the name of the quori ancestor: Lanharath is Lan of the lineage of Harath. Quori spirits do have gender, and a newborn kalashtar inherits the bond to the spirit of the parent with the matching gender. Kalashtar can interbreed with humans and half-elves; if the gender of the child matches the kalashtar parent, it inherits the bond and is born a kalashtar. Otherwise it matches the race of the mundane parent. Kalashtar racial traits, including their distinctive appearance, stem from the touch of the quori on body and soul. There is no such thing as “half-kalashtar.”
The quori founders no longer exist as true individuals; instead they live within the communal subconscious of all of their physical descendants. Members of the lineage cannot actively used this mental bond, but they share the same dreamlike memories and typically have the same opinions and moral values. Two Vakri kalashtar will find that they can anticipate one another’s actions, that they finish each other’s sentences, and that they naturally gravitate toward the same sides of an argument. Kalashtar with the same lineage are not mental clones, however. Each individual’s life experiences and human soul shape his or her character and personality, and alignment and behavior vary from character to character.
(Races of Eberron, pg. 59)
Here we see numerous references to kalashtar giving birth to kalashtar bound to the same quori spirit, references to “all of” the kalashtar bound to a given spirit, “Two Vakri kalashtar,” and so on. Nothing seems to come out and say it, but none of this would make sense if kalashtar could only exist in one-to-one relationships with quori.