I was sure I've mentioned somewhere:
The multiply number NOT include the original piece(s).
So, on both methods, you have to have on plan 1(the original) + a group of inserted numbers of pieces(only those which can be grouped).
For the curved method try to move the original out side the curve,
OR
verify in the furniture list if the original is grouped with the multiplied items.
I know it doesn't but who knows??