this is a bit odd, right?
My cousin (not been in touch for years after our fathers fell out) got married recently. His wife has the same name as his sister. So now his unmarried sister and his wife have identical names (and are both blonde, with blue eyes, and of a similar height). His sister's name is not a common one. So it's not a case of "oh, well, lots of people are called Sarah so this was always a risk...".
This is a name that, at its peak, was barely in the ONS top 100 girls names.