Yes, Klingon for the Galactic Traveler
specifically mentions that before being unified by Kahless, the Klingons of Qo'noS belonged to many disparate groups, "with different customs and sometimes different languages.", and that to this day there exist dialects so different that their speakers can barely communicate with one another.
What we call tlhIngan Hol
("the Klingon language") is actually tlhIngan wo' Hol
("the Klingon Empire's language").
One also sometimes speaks of tlhIngan ta' Hol
("the Klingon Emperor's language"), in reference to the standard dialect at any one time.
One famous Klingon language is klingonaase
This was first used in The Final Reflection
by John M. Ford, before tlhIngan Hol
and ridged foreheads had been invented.