Information, indictments, trial, and sentencing for violations of this chapter may allege any number of violations of their provisions against one person and join one or more persons as defendants who it is alleged violated the same provisions in the same transaction or series of transactions and which involve common questions of law and fact. The several charges shall be set out in separate counts and each accused person shall be convicted or acquitted upon each count by separate verdict. Each accused person shall thereafter be sentenced upon each verdict of guilty. The court may consider such separate verdicts of guilty returned at the same time as one offense for the purpose of sentencing as provided in this chapter. The court may grant a severance and separate trial to any accused person jointly charged or indicted if it appears that substantial injustice would result to such accused person unless a separate trial was granted.