Let's say I went to the doctor in the morning, greeting the venerable professional with a sincere "こんにちは", and that I left him after he healed my terrible headache.
Now let's say that during the same morning my friend had an accident involving hammers and nails, and requiring me to bring them to that same doctor.
Would it be acceptable to greet my trusted health provider with a "こんにちは" again, or would it sound weird? What, if not "こんにちは", could I say instead?