My doctor prescribed wellbutrin er 150mg twice a day. isn't er supposed to be once a day?

Confusing: "USP officially designates the SR formulation as“ bupropion hydrochloride; tablet, extended release.” The generic name for the XL formulation is “bupropion hydrochloride; tablet, extended release.” Although the generic drug names are the same, the two products are not therapeutically equivalent or interchangeable." REF: https://psychnews.psychiatryonline.org/doi/full/10.1176/pn.41.6.0016