No, not dual playfield. I mean for example...Open Deluxe Paint on Amiga and open a 64 Color picture............then whilethat is running, drag down the window to reveal Workbench.......now Open a Multitasking game that can drag the window down....while playing that game drag its window down half way to reveal Deluxe Paint behind it....now your Monitor/TV is showing more than 64 colors on screen at once.....now imagine Deluxe Paint is just a 32 color or 16 color animated background on its own public screen. And imagine The WB game you opened infront of it was created with transparent holes or areas where the scrolling background would be but you pruposely left it blank and color Zero (Transparent on Amiga?) Now you can see the public screen behind it which is running a 32 or 16 color scrolling background. Your game now has more than 32 colors or more than 64. This is usually called Multitasking on Amiga and it tricks the Amiga to the Human eye regardless of what we think the technical limits are, to display more colors. I believe Broadcast Titler 2 does something like this where is takes mutliple screens at multiple resolutions and colors and mixes them together to show more than 128 colors on screen on an OCS Amiga 500.
Viewing post in Addams Family Amiga: The Backgrounds Edition comments
The Amiga can change the bitplane data and colours as each horizontal line of the screen is drawn. That's how AmigaOS achieves that effect of multiple windows being drawn "in front" of each other - what you're really seeing is a lot of Copper instructions to change the bitplanes and colours as each of those windows is displayed.
That doesn't, however, mean that one window could have holes/transparency in it to display what's underneath, because the hardware can't work that way.
Does not have to have “holes”. The most front screen in the foreground can be where the main character and enemies dwell. The Upper part of the screen (clouds, parallax clouds etc) can be the screen behind because the front screen is halfway pulled down revealing the one behind, both syncronized and to the player they look as one. I really suggest Amiga coders look at Broadcast Titler on the Amiga and how it is achieving what it does.