Can someone fill a script in someone elses name?

No, if this were so, the medicine would just be "over the counter". Prescriptions are written out by a doctor for that specific patient for their specific condition. Also, you should never take medicine prescribed to someone else, this can be very dangerous. When the doctor wrote out the prescription, he/she knew all of that patients conditions and other medicines they were on, however he/she has no prior knowledge of any of your info.