Would Spotting After Taking Duphaston For Two Weeks Imply Implantation Bleeding?

Hi, I have taken letrozole for 5 days starting from 2nd day of my cycle and on 18th day of my cycle I have started duphaston which is adviced for 15 days. On 13th day of duphaston I have started spotting, does this means implantation bleeding or period. I am still continuing duphaston