Fix RGB/RBG mixup that caused strange artifacts.

Shaders/DepthPeeling/final_dual.glsl

@@ -12,5 +12,5 @@ void main()
 	vec4 cb = texture2D(BackSceneTex, vTexCoord);
 
 	// combine front and back color
-	oColor = vec4(cf.rgb + cb.rbg * (1.0 - cf.a), 1.0);
-}
\ No newline at end of file
+	oColor = vec4(cf.rgb + cb.rgb * (1.0 - cf.a), 1.0);
+}