One oximeter shows 92 spo2 level another shows 98 which is correct? 50 year old covid positive patient ?

All readings have to be correlated with circumstances and actual symptoms in order to be meaningful. While both values appear normal, 92 is borderline, clinical status and further readings in dynamics will help clear the differences and assigning accurate readings to one or another, would continue checking with the one believed to be more accurate. Would trust the lower value if short of breath.

Watch the trends on the chosen device. If level is steadily declining, head to hospital