I would return them also. I am just one of those way honest people - my conscience wouldn't let me keep the extra pills. Whenever I have had an opportunity to steal, cheat, whatever, I have always thought to myself that even if no one knew about it or caught me, I would know - and that's enough to keep me honest.
I wanted to add my 2 cents about counting pills. The pharmacy I go to has a sign that says to count your pills before you leave because they are not responsible once you leave the store. Ok, I get that. Well the other day, there was a woman in there who picked up 4 prescriptions - all pain meds. She went to the little side counter and proceeded to count out one-by-one each of her scrips - 240 percocet, 120 oxycodone, 90 oxycontin, and a box of fentanyl patches. I remember what they were and the amounts because she (loudly) repeated the info several times during the process of counting them. She lost count more than a few times - I left for a bit, came back, and she was still counting! It was a little bizarre. Now I have to add, I make it a point to never "pre-judge" someone - I know very well that many of us have "invisible pain". But am I the only one who thinks that is a whole lot of pain medication for one person? I saw no signs at all of any discomfort, injury, or bandages on this lady. Aside from the strange counting thing, she looked totally healthy, mobile, and agile. You would think if she had a condition that required that much pain relief, there would be some kind of sign of pain or discomfort. Oh well, sorry I digressed a little!