The doctor is saying that he or she will switch him to a short-acting medication if you want 2 doses. What you are probably wanting is to keep the long-acting medication and add a short-acting “booster” dose in the afternoons. That is very common.
The ADHD Witching Hour: Surviving the After-School Medication Crash
Penny
ADDitude Community Moderator, Parenting ADHD Trainer & Author, Mom to teen w/ ADHD, LDs, and autism