Biplanes in this sim are modelled as having a single pair of wings. The biggest issue will be where you position that fake pair of wings as it will influence ground effect. It is still better than FSX where biplanes were apparently modelled as a single wide wing.
More to the point - when people say flying a biplane they are often meaning flying a taildragger. It is important to distinguish the two as not all tail draggers are biplanes, and whilst rare, tricyle biplanes do exist.