Taken at the same time. This better sensitivity, combined with much nicer feeling swabs, is why I buy Abbot PanBio instead of using the crappy free BTNX tests from the grocery store.
Levitt Safety is Canada’s Panbio distributor - $52 for a box of 10: https://www.levitt-safety.com/Product/IA41FK701
Of course this cost is out of reach for many, and free BTNX tests are far better than having no tests.