Vertex blending problem - Height Lerp

Hello
I have problem with vertex painting via height lerp.
Material work fine but Height Lerp give me a weird results with R and G channel, the both channels collide once i start painting over one of these channels, “red channel should end at the border of the green channel and conversely, but both want to overlap each other” result is dark vertex color and extreme heightmap on my material.
I tried a few other setting but unfortunately no good result.

Basic material include basic texture and use Blue channel for water puddle painting.
Material function include Red and Green channel for moss and stone surface painting, this vertex surfaces collide.

Basic material:

Material fucntion:

When R and G channel collide:

249995-hlerpprob-small.gif