Reason why Regenerate Health (S/M) and Damage Stamina (M) Regeneration should not use the same <iDurationBonus>:
 
A poisons/potions magnitude is determined by the following formula:

Magnitude =Base_Mag *4 * (Game setting fAlchemyIngredientInitMult)
(1.5^(Alchemy_Skill/100))*(1.5 is the game setting fAlchemySkillFactor)
(1 + Fortify_Alchemy/100)*
(1 + Alchemist_Perk/100) *
(1 + Physician_Perk/100) *
(1 + Benefactor_Perk/100 + Poisoner_Perk/100) )

A Damage Health poison you brew grows in magnitude as the game (Skill, Perks) progresses.
 
What about potions like invisibility? You can't be more invisible than ... invisible. Let's call this type of potions "fixed effect potions/poisons". In this case the formula above changes to:

Duration=Base_Dur *4 * (Game setting fAlchemyIngredientInitMult)
(1.5^(Alchemy_Skill/100))*(1.5 is the game setting fAlchemySkillFactor)
(1 + Fortify_Alchemy/100)*
(1 + Alchemist_Perk/100) *
(1 + Physician_Perk/100) *
(1 + Benefactor_Perk/100 + Poisoner_Perk/100) )

Damage Stamina (M) Regeneration is also a "fixed effect poison". The second formula applies and thus all ingredients
should be ReProcced to have a ~5 second duration.
 
If you use <iDurationBonusRegen>118</iDurationBonusRegen> to give Regenerate Health (S/M) potions 120 seconds duration, then you will also give Damage Stamina (M) Regeneration poisons extreme values.

At 20 Alchemy with no perks a Damage Stamina (M) Regeneration poison will have ~488 seconds duration.
 
For this reason I switched Regenerate Health (S/M) into the <Fortify> departement. They will - like Fortify Potions - grow in magnitude with a fixed time of 120 seconds.