Two Tributer Monster?

Ok, this question is maybe a little simple...
May i tribute a two tributer monster such as double coston and one another monster to tribute summon The wicked avatar (need 3 tributer monster to normal summon)?
In this case, Double coston is a 2 tributer monster for dark monster like The wicked avatar?
thanks for the attention

I guess you can. Not sure. There may be a rule againist this. But wikia says this for OCG:

YGo Wikia OCG Ruling for Double Coston wrote:You can Tribute Summon "The Wicked Avatar" or "The Wicked Dreadroot" by Tributing "Double Coston" and one other monster.[1]

Double Coston effect wrote:This card can be treated as 2 Tributes for the Tribute Summon of a DARK monster.

So yes, it will take up 2 of the 3 tributes necessary, meaning you can summon Avatar/Dreadroot/Eraser by using Double Coston and only one other monster.

Ok, thanks, both of you just explain it to me without any problem, how high your acknowledge of YGO's rule so the problem solved