No idea but on the last Diamond UK open day we were invited to look through their stock & note down any we wanted to order, we weren't allowed to pull copies as their staff would do this later for us to keep their stock levels correct.
We were after a copy of Wolverine Origins #2 for a customer but found they had none left.
However, they did have 2 full longboxes (600 copies) of Wolverine Origins #2 - 1:100 Canadian Flag Variant! We weren't allowed one.
They were blown out at 25 pence each about 5 months later & we managed to get 50 copies.
This is not a limited incident either, still happens quite a lot