Can pcos cause high androstenedione and normal testosterone levels?

Yes, but. Testosterone levels frequently normal but free testosterone is elevated because of a lower percent of testosterone being bound to sex hormone binding globulin!
Sometimes. Normally androstenedione and testosterone levels mirror each other as aromatase is the enzyme that converts each into its estrogen and estradiol, respectively. So they really should be the with in normal limits at the same time.