This division shall not prevent the acquisition of property for public use and the making of public improvements in a single proceeding if the law under which the acquisition and the improvement are to be made authorizes such acquisition and the making of such improvements in a single proceeding.

Where a single proceeding covering both the acquisition and the improvement is contemplated, only a single proceeding covering both the acquisition and improvement need be taken under this division, and its provisions shall apply to such proceedings in the same manner as they apply to proceedings in which only the acquisition of property or the making of improvements is involved.