When you RMA a drive, anything can happen...
1) you could get the same disk back ("nothing is wrong with it"), and risk having to pay some tech fee. Never happened to me.
2) you could get a "refurbished" drive, happened to me twice with IBM (fsckers).
3) you could get a brand new drive (happened with the single maxtor disk I've RMA'ed).
If the drive temperature is off in the second box as well, and there's no firmware update or something, and you're going to replace the drive anyway, go for the RMA. A little trick that makes sure you'll get a new drive is to hook it to a PSU you don't care much about, then short-circuit the drive with a screwdriver until it stops working completely.