Hi,
The tracker collects data points at regular intervals. In this case, about every 160ms to 170ms. You cannot necessarily conclude from a change from one line to the other that the participant kept looking at the same point during that interval: not only because those are just estimates from the model, but also because the participant might have started looking elsewhere early after the former data point was collected, but the model just registered that on the next cycle, and so it shows up in the file only about 160ms later
Based on an average interval of 165ms, what you can say from the lines you posted is that the participant was (estimated to be) looking at the left item for at least 2581-2250 = 331ms and at most 331+(165*2) = 661ms. As for the right item, all you can say from these lines is that the participant was (estimated to be) looking at it for any duration between 1ms and ~330ms
Jeremy