Okla. Stat. tit. 21 § 61.1
When any person is convicted of two (2) or more crimes in the same proceeding or court or in different proceedings or courts, and the judgment and sentence for each conviction arrives at a state penal institution on different dates, the sentence which is first received at the institution shall commence and be followed by those sentences which are subsequently received at the institution, in the order in which they are received by the institution, regardless of the order in which the judgments and sentences were rendered by the respective courts, unless a judgment and sentence provides that it is to run concurrently with another judgment and sentence. This section shall not affect the credits allowed under Section 138 of Title 57.
Okla. Stat. tit. 21, § 61.1