Roark is correct, the A and B signify the two channels inside outdoor PurpleAir devices. You can average them to get a single value, which is what is done for map dots. More information is available here: What are Channel A and Channel B?
EDIT: Upon review, if you’re saying both the A and B channels returned data twice for the same time period, this was an issue in our system. It should be fixed now and shouldn’t happen moving forward.