Jason,
That's one of the configurations still being tested. The other is to single-bevel the Tanto tip on the side opposite the edge's single-bevel. It's when both are on the same side (for that half of the blade) that the tendency to spin-off a bone surface begins to show up.
The difference is of little consequence on rib hits on open-rib animals. There, the BH just slips off the rib to enter at the next intercostal space. However, it can be a problem on bones with larger flat surfaces, such as a scapula, or on highly curved bones, where redirection of the arrow's path of penetration can be of marked degree.
Ed
TGMM Family of the Bow