Every now and then, I'm reminded that λαλέω means "to say or speak", especially when reading the New Testament. It seems possible that λαλέω derives from the same PIE stem as λέγω through reduplication. Wiktionary, however suggests otherwise, claiming that λαλέω derives from *leh2- and λέγω from *leg-.
Is the similar meaning of the two words a coincidence? Or is there some genetic relation? Furthermore, are there any semantic nuances between the two, e.g. cases where one is appropriate but not the other? Is λαλέω common in the Attic dialect or only in Koine?
The Latin cognates are lallo and lego, and although we find a similar meaning between lallo and λαλέω, we do not see a semantic similarity between lego and λέγω. At least not in the sense of speaking. I wonder why this is.