Is the prostration of forgetfulness (sujud al-sahw) obligatory if one inadvertently repeats "Rabbī" before "Rabbana wa laka al-hamd" when rising from bowing?

Saying "My Lord, my Lord" before rising from rukoo' (bowing) is not prescribed in prayer in this form, but it does not necessitate sujud as-sahw (prostration of forgetfulness). The prayer is valid, and sujud as-sahw is not required.