Re-selling damaged goods

I bought a pair of shoes from Mr Price in Riverside Mall Nelspruit. There was a tear in one of them and i took them back to Mr Price in Illanga Mall in Nelspruit. they refunded me for the shoes without any problem as they did not have another one in my size. Then 2 weeks late i walk into Mr Price in Illanga Mall and see they have a pair in my size, i was in a hurry so i grabbed them and paid and left. Only to discover the next morning that i bought (of the shelve) exactly the same pair that i previously returned. Who does this? why do you put stock on the shelves if you know it is damaged!!! This is unacceptable, now i need to go and exchange the same ****** pair of shoes for the second time!!! unacceptable!!!