Well i saw a post baout somoen eelse selling fake sony duos os i thought i would put this together from different resources on the net and try to help a few people out
First things first, what does a fake duo look like ?
The seal
The seal is also a very important factor, on the real blister backs the seal is
rectangular whereas on the fake ones the seals are round and contain glue int hem to help keep it shut.
Holograms
The holograms are very good on the fakes so this in no way makes it real just because it has a hologram!dont be fooled by it.
Capacity
regarding 2gb cards the fakes are coded to make devices belive there is 2gb of capacity whereas they really have something like 1gb, when put into the device this is what comes up
1959MB-FAKE
1948MB- FAKE
1909MB - REAL
1910MB- REAL
To test the total storage, whack it into your pc and try to convert a few big files onto your card, if it maxes out at 1 gig your cards fake!
Transfer speeds
The real MS pro duos (high speed) will transfer at 80 MB/S whereas the fake ones will max out at about 65MB, if you have one and ur still not sure from reading this if its fake then time the speed it takes to transfer a file.
The Card itself
Take a look at the card itself, on a real card you can run your finger over the wording and feel it is slightly ingraved onto the card, on a fake one it is printed on cheaply and will quite possibly rub off if you push down hard.
From what ive read the cards are mainly coming from taiwan but ive been offered them from a lot of chinese sellers.
Hope this is helpfull!
All about fake Sony Duo cards
just above peoples names, just for future reference 
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November 2009
