Did the recipe call for soda and you used powder? I think it means your cookies might puff too much and be cakey? If that's what happens in your test batch you might try rolling the dough real thin - btwn wax paper if need be, or lots of flour on your surface and pin. Cut into squares and bake those and see if the puff/thinness cancel each other out... Baking powder is baking soda plus cream of tartar (acidity) so if you double up your recipe you could reduce whatever the acid is in your recipe(perhaps molasses). Good luck!

Depending on how much of the two you used, that could either be a disaster or a happy accident. I agree, no way of knowing until you bake and see! Good luck!

I agree with anyone--just bake a few and see what happens! You could double the rest of the ingredients and reverse the baking powder and soda to balance but you'd have to be sure that you mixed them up in the first place. Good luck!

Sorry, but in my opinion there is nothing to do at this point but bake and see what the outcome is. Good luck!