Maternal 1st cousins showing different levels of mtDNA

[Thorbjorn]

My first cousin and I, our mothers were sisters, come up with HV4a (me) and R0 (him). I know R is the ancestor haplogroup of H & V, but I'm curious why 23andMe reports our mtDNA at different levels.

[Joey37]

Perhaps you were tested on different chips. I have a cousin who tested on an earlier chip and is still at R-L51 for a y haplogroup (origin 4100 BC per YTree) while I am at R-YP445 (origin 150 AD per Ytree) on the latest chip. (We're not male line cousins; I am R1a and he is R1b; he's from the male line of my Nana's maternal grandfather)

[Thorbjorn]

Perhaps you were tested on different chips.

Yes, we must have been. I was on V4 in 2015. He must be on V5 since he just showed up in my DNA Relatives list this year. I would have thought that if anything his result would be more detailed than mine. But what do I know? ("... nothing Jon Snow", which is why I ask :D).