I understand what you are saying, but all it takes is to ask why there are 580 stamped hd650 sold and if they know why.
headroom could face more complaints if more found out that they actually received 580 stamped hd650's.
maybe it's a good idea for headroom to check their stock and see how much of these headphones made it into their stock. If they find more, it seems valid.
Thus far one from headroom has the 580 stamp on it. So, it seems they are allready involved in this.