Is that possible to change price tag of same item??? cheating?

i bought levis jeans at mecy`s and i got a same jeans for my birthday gift. so i decide to cut the price tag of the new jeans and place it on the old one, and then return the old 1, and i just wanna keep the new1. so is that possible if i place the price tag of the new jeans to the old1?? the jeans are both levis 511. I WILL APPRECIATE IT IF U JUST TELL ME HOW