Matthew Panzarino for TNW:

So we contacted Apple and it has confirmed to us that the numbers released about the iOS App Store, currently at 18 billion downloads, with 1 billion downloads a month, are uniques.

Yesterday I contacted Apple and confirmed that the 100 million Mac App Store downloads were unique and did not include Lion, updates or downloads to other Macs. Panzarino took it a step further and confirmed the same for the iOS App Store.