All persons in actual possession of any portion of the several subdivisions of any section of land, according to the government surveys thereof, may be made defendants in one action: PROVIDED, That they may, in their discretion, make separate answers to the complaint, and if separate issues are joined thereupon, the same shall nevertheless be tried as one action, but the verdict, if tried by jury, shall find separately upon the issues so joined, and judgment shall be rendered according thereto.