I had never heard of there being two unrelated Colored families of Chavis in VA...
Could it be that it was the same family, and some got free earlier than others due to there being a limit on how long a person would be enslaved or indentured? My understanding is that early colonial rules were different than later, and even Africans who were enslaved only had to be that way for a number of years and then were freed to live equal to anyone else there..
That could explain a lot of things...