Маловероятно, что это ошибка. Просто редкий и малоисследованный/малотестированный субклад.
mtFull очень надежный тест.
The History of Slavs Inferred from Complete Mitochondrial Genome Sequences
Marta Mielnik-Sikorska, 1 Patrycja Daca, 1 , ¤ Boris Malyarchuk, 2 Miroslava Derenko, 2 Katarzyna Skonieczna, 1 Maria Perkova, 2 Tadeusz Dobosz, 3 and Tomasz Grzybowski 1 , *
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3544712/The analysis of these haplogroups confirms the presence of Siberian (C5c1, A8a1) and Ashkenazi-specific (L2a1l2a) mtDNA lineages in Slavic populations.
Within A8a, Polish and Buryat haplotypes are clustered together into subhaplogroup A8a1, defined by 152-6962-8865-12777 motif .... The presence of the A8a1 haplotype among Poles supports the previous hypothesis that occurrence of A8a lineages in central Europe may reflect the probable medieval migration of the nomadic tribes from Siberia
In particular, among Poles we show the presence of A8a1 haplotype, which may reflect the probable medieval migration of the nomadic tribes from Siberia.