What is the name given to the card move where two cards are turned and
displayed as one?

jas_sanghera,

Thank you for your question about card tricks.  As a fan of sleight of
hand in general, and card tricks in particular, this was a fun
question to research.

The trick you are referring to is called a double lift. You can learn
more about this trick, and it's variations, at
http://ps.superb.net/cardtric/sleights/dlift.htm

Thanks again for your question and if you need any further
clarification, please let me know.

Regards,

-THV

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card trick two cards show as one
"double lift"+ card trick