If the sprite name is changed in a dehacked lump's text section, Vavoom now doesn't replace only the sprite but the whole item and it's properties. For example if the deh patch defines:
Text 4 4
Vavoom (without models) shows the invis. sphere sprites (PINS) for all blue health potion bottles (BON1). With models you see the normal health bonus bottles.
But when you pick that item up, Vavoom gives you the invis. sphere and it's "Partial Invisibility" pick-up message.
With the original dehacked-Doom game you'd have got only the health bonus with it's "Picked up a Health Bonus" message. So only the sprite's name should get changed.
Some TCs use this feature to introduce completely new spritenames. Such as:
Text 4 4
but Vavoom can't pick that shotgun up at all.
A short demo wad here (the deh lump is merged into the wad). If you have models check console command r_models with both values 0 and 1.