OK, I am stumped.
How do I remove the full height adaptor and put the low profile adaptor on the X520 SR2 Dual 10Gbe NIC?
The holes in the full height adaptor are too small let it slide off the flared fiber connectors - a matter of a millimetre or more so a little bit of force won't help.
The markings on the box are Version: E68788-003, E10G42BFSR.
In the words of the immortal bard, Doh!
This is why you don't let software guys near hardware. All I had to do was remove the GBIC and the bracket slides off real easy.