The maximum daily dose of sertraline is 200 mg. Since you took the next dose about 12 hours after the previous one, the risk of severe overdose is lower, but the total amount taken (300 mg over about 12 hours) exceeds the recommended maximum daily dose.

Watch for symptoms such as drowsiness, dizziness, nausea, vomiting, tremors, restlessness, palpitations or increased sleepiness. If you experience severe symptoms, loss of consciousness, seizures, severe agitation or difficulty breathing, call an ambulance or go to the hospital emergency department immediately.

Since the situation took place last night, if you did not observe any worrying symptoms at that time, today take the tablet at the usual time and continue taking the next ones according to the planned therapy schedule.

I attach a link to a helpful post:

https://www.gdziepolek.pl/artykuly/czy-bac-sie-dzialan-niepozadanych-lekow

Here you can check the availability of the drug and make a reservation at the pharmacy:

https://www.gdziepolek.pl/produkty/7628/asentra-tabletki-powlekane/apteki