sigh, anyway I've switched to another site (786gifts) and they asked me the same but they gave me the option to hide my personal info except name and address: "If you still feel insecure, please feel free to over line (hide) any information such as credit card number, license number, passport number or any other information you don't want to display. We have no problem with that, we are only concerned with the name and address information that you have already provided us while placing your order." So I sent it (passport copy) as Junaid001 told that it was a normal procedure. I hope it'll go smooth... I'm a bit worried.
emarkaz should have asked for card only i guess no use for passport.
you shouldn't be worried much, your basic information is already visible to owners/managers or staff depending upon security clearance of staff what they actually needed it for was making sure you are the one who ordered and you own the card.
normally businesses ask for card copy with authorization with few digits of card truncated or deleted for security reason.