Normally, bleeds don’t stack if it comes from the same source (like using Rend twice) but they will stack when they come from two different sources (like using Flay then Rend). Applying multiple bleeds normally puts more than one number on the enemy. However, Aspect of Berserk Ripping doesn’t seem to do so with Rend. Rend deals some normal damage and then applies a bleed, but only one number appears (and doesn’t seem to be increased even if I crit with the direct damage).
This is pretty terrible since all of the bleed skills have low base damage as it is and Berserk Ripping doesn’t take into account any boosts to Damage Over Time or +Bleed Damage.