Is it obligatory to repeat the prayers and fasting of the two days during which the brownish discharge mixed with blood was observed, or do these discharges not necessitate repetition?

We did not definitively state the necessity of making up the fasts (qada'), but rather clarified when the recurring blood is considered menstruation and when it is not, and the ruling on brownish discharge (kudra). If what you saw was menstruation, then making up the fasts is obligatory according to our fatwa. However, if another trustworthy scholar has given you a fatwa stating that it is not obligatory, then follow the one you trust, for by doing so, your responsibility will be discharged.