Inconsistencies of a purported probability current in the Duffin–Kemmer–Petiau theory

The Duffin–Kemmer–Petiau (DKP) equation with a square step potential is used in a simple way with polymorphic purposes. It proves adequate to refuse a proposed new current that is currently interpreted as a probability current,to show that the Klein paradox does exist in the DKP theory and to revise other minor misconceptions diffused in the literature.