I think you will find it will have been exchanged rather than repaired. Check the serial number. If that is the case, it is often the way they do things nowadays; though the replacements are always tested and meet 'New' standards and carry the full guarantee from the point in time you receive it. I stand to be corrected on this so I am repeating what i recall from reading other questions.
Sadly, it's still my original iPhone 5. No replacement (I recognise the dents on the bezel)! I wish I could know because everything has been pretty normal so far in terms of recharging the battery. The phone still gets pretty hot on the back.
I wish there was a way I could know if the battery is new. I just hope my battery won't still die after 5/6 hours! Fingers crossed