Wyo. Stat. § 41-4-328
Upon such hearing the board shall have authority to modify or alter the original order in such respect as shall appear just and proper. But it shall not be necessary for an application for rehearing to be filed to entitle any party to an appeal. Upon such hearing the board shall also have authority to permit, upon good cause shown, the correction of the testimony of any party or witness, if it shall appear that a mistake has occurred therein, but no other new evidence shall be received at such hearing unless it shall be shown to the satisfaction of the board that the same is material, and has been discovered since the taking of the original testimony and could not with reasonable diligence have been discovered before that time.
W.S. 41-4-328