Borghild Jonsdatter Kvamshaugen 1/17/1851-10/17/19

I have traced my great-grandmother Borghild Jonsdtter Kvamshaugen Lappegard's 1/17/1851-10/17/1910 mother - Rangdi Olsdatter Kvamshaugen Onstad 1817-1887 and ALSO her father John Jensen Ohnstad 1812-1886 back to two sons of Sander Sanderson Roo 1604-1677. Rangdi's side goes back to Knut Sanderson Roo 1632-1711 and John Jensen Ohstad's side goes back to Guttorm Sanderson Roo 1650-1711. So it looks like I have a double relationship with the Roo's! Does this sound all right with you? Is that possible? or am I in need of correction?