Skill cumulative effect...?

Hi,

I did a search on that question and didn't find anything. Are skill effects cumulative? For example: if I cast Conjure Phantasm and Crippling Anguish on a target, does that mean that the target will be getting a total of health degeneration of 8 (5+3) ?

From what I have seen yes. though not two of the same skill ,say from two mesmers both casting phantasm (-regen on health.)