Is a biplane without dihedral more stable than a low wing monoplane without dihedral? I was wondering if a biplane's top mounted wing created the same stability effect as that of a high wing airplane?
Also, would the unstable effects of the low wing cancel the stability provided by the high wing and condition the biplane to behave like a mid wing airplane? If yes, is it one of the reasons why manufacturers make the top wing longer or is it just extra length provided to generate more lift and replace that lost due to wing interference?
This questions have been bugging me for some time now. 
Someone pls clarify me.
Maybe I missed something...
Narrow answer: Yes, it is.

But no aircraft designer in his right mind would build an unswept low wing aircraft without dihedral. So this question is misleading.

Please look here why low wing aircraft need more dihedral.

Please read here why a low wing aircraft is just as stable as a high wing aircraft. The high wing does not entail more stability!