I definitely didn’t think you made it up. And yeah that site does match 20 Adderall XR to 50, which is very odd because it also says 20 of the other Adderall is too high for a Vyvanse equivalent. For Adderall XR it also lists a maximum dosage of 30, which is not true. I think they’re treating the XR as two doses, and halving to accommodate that? That is definitely not how I’ve ever had it discussed or prescribed by my doctor, or fulled by a pharmacy. And it’s inconsistent with Vyvanse which is also XR and always treated as a single dose.

In any case if you were taking Adderall XR “20” and it was actually two doses (40) that would be equivalent to the Vyvanse.