Hi. Docherty and Doherty are anglicised surname from the same Irish and Scottish surname (way more common in Ireland though). Both pronunciations are valid though the K-sound is more common in the UK. There is actually three ways to say the first part. 1. Like Doctor - Doc-er-tee 2. Like Doughnut - Doh-er-tee and 3. Like Dawn - so Daw-er-tee