Duplication problem with Post process

Hello,

I use a post process with a material to give a marine effect, so I activated the “stencil” and I activate / deactivate the effect of post process on my jellyfish (my character) because he must not suffer the 'effect.

My jellyfish is a 2D flipbook, I attach the materials, the rendering, the node and the flipbook as an attachment,

my problem is that as you can see in attachment, my jellyfish is duplicated, I get one with the effect and a second without …

I do not see why I’m getting this …

Regards,
NicolasBrg

The rendering:
file1.png

The material of Post process:

the node for enable/disable stencil:
file3.png

And the FlipBook: