I haven't played HU for the most recent patch, but if PStrike is still level 6, and PNova is still lvl 36, then it's not possible for both to spawn on a white item.
Here's a freshly googled source of information on
staffmods. They claim that the skill's tier is based on the skill's ID number, so it should be possible to swap skillIDs around in skills.txt so that low level skills can appear with high level skills. This would cause the SkillID column to no longer be sorted though, which might be a problem. Swapping the rows might be a problem since some functions (Moncurse?) appear to locate skills by their row. It would be neat if this were tested and perhaps applied to a later patch.