Have a look at this advanced offer which you may want to consider in your shop if you have our POS Software.
We did this based on a study here
As it shows that it works better than "Buy two, 10% off both".
You would think that they are the same, what is the difference to a customer of
1) Buy two and get 20% off the cheaper one.
2) Buy two, 10% off both".
But the answer is no.
The study showed that the sales number were about the same in both cases. Yet shoppers, when offered the "Buy 2 and get 20% off the cheaper one" offer, tended to choose a second item that is more expensive. This increased their return from the 20% discount.
So for the retailer, the sales total went up.
Try it out and let me know how it went.