Do temporary hit points gained from these auras stack?

[Soul Devourer]

Do temporary hit points gained from multiple killings in one of these auras stack? And what about CL in the second one?

Aura of Succumbing (feat)
Benefit: As a swift action, you can expend one of your uses of channel energy to emanate a 30-foot-radius aura of succumbing for a number of rounds equal to your effective cleric level. Dying creatures in the area take 1 point of damage per die of your normal channel negative energy damage at the start of your turn each round. A successful Will save (DC equal to the DC of your channel energy ability) halves this damage. Whenever a living creature dies while within your aura of succumbing, you gain a number of temporary hit points equal to that creature’s Hit Dice. These temporary hit points last for 1 hour.

Death Knell Aura (4th-level spell)
Range 20 ft.
Area 20-ft.-radius emanation, centered on you
Duration 1 round/level (D)
Saving Throw Will negates; Spell Resistance yes

DESCRIPTION
You gain a shimmering gray aura that feeds on the souls of creatures who die within it. The aura sheds light as a candle. If a creature at –1 or fewer hit points is within the aura at the start of its turn, it must save or die, granting you the benefits of death knell ("you gain 1d8 temporary hit points and a +2 enhancement bonus to Strength. Additionally, your effective caster level goes up by +1").

[Soul Devourer]

Bump

[wraithstrike]

Temporary hit points from different sources stack, but they shouldn't stack from the same source.

[Avoron]

Temporary Hit Points: Do temporary hit point from the same source stack? wrote:

No. Generally, effects do not stack if they are from the same source (Core Rulebook page 208, Combining Magical Effects). Although temporary hit points are not a "bonus," the principle still applies.

This prevents a creature with energy drain (which grants the creature 5 temporary hit points when used) from draining an entire village of 100 people in order to gain 500 temporary hit points before the PCs arrive to fight it.

Temporary hit points from different sources (such as an aid spell, a use of energy drain, and a vampiric touch spell) still stack with each other.

[Soul Devourer]

Thank you very much for your replies. Well then, both the feat and the spell (if even the CL increase does not stack) are pretty useless, as is the Souldrinker PrC