Tone Boards for Double Sided Pot Calls

[dogbox]

Does a double sided pot call need a tone board?  For example, an aluminum top side with a slate bottom side, would the slate bottom work as the tone board or would you need a separate tone board in the middle of the call?  If a separate tone board is needed, I'm guessing it should be positioned toward the top call surface?  I'm thinking about trying to build a double sided call and I trying to get the call innards figured out.

Any info will be greatly appreciated. 

[mastevt]

Mine has a soundboard for each side.