Tried DualPlayfield

I just tried DualPlayfield example in the Blitz2 (dualpf.bb2) today. I think this is really nice short program to see how it works. This is creating two 3bit planes for foreground and background bitmap. Coplist is initialized to 6 bit planes with dualplayfield and smoothscroll. I also tried 4 bit planes bitmaps and initialize coplist with 8bit planes for AGA.

Bitmap 0,640,512,4
...
Bitmap 1,640,512,4
...
InitCopList 0, $10038

I'm going to implement current my test program. I need to confirm about palette too. The palette for sprite is placed at right after bitmap's palette. When I use dualpayfield, the palette seems like initialised 32, 16 for foreground + 16 for background. So where the palette for sprite should I placed to? 16 foreground +16 background +16 sprite ? 

Memo: When I tried 2bit planes for foreground and 4bit planes for background, it shows some noisy bitmaps. Maybe unsupported?