Okla. Admin. Code § 325:25-1-17
In no case shall more than two (2) horses having common ties through Ownership, training, or lease be entered in a purse race (overnight). When making a double entry, the second same Owner entry drawn shall have no preference over any single entry in purse races, excepting a preference over an "in-today" horse. At the time of entry, a preference must be made to the end that each interest may have an entry in each division should the race be divided. For different Owners, an Organization Licensee, with approval of the Stewards, may allow for each entrant to have an equal shake to draw into a race providing the horse(s) have preference. If a race is to be divided, an additional conditional entry may be accepted from any interest. Each such entry may have a joint entry. All divided races will be considered separate races.
Okla. Admin. Code § 325:25-1-17