When I bought my phone (Wasel prepaid) I was required to hand over a passport copy AND a copy of my residency visa.
My suggestion is to make 2 coloured passport copies (for yourself in case of loss etc) and 10 b&W, when Emirates send you the temporary visa in your email, make at least ten copies of this also.
Everywhere asks you for these- for the bank accounts, for internet, for BUYING the phone (not even to set it up, just to buy the pre-paid)
You'll make your life much easier by always having copies at home and also carrying one or two extra with you at all times so you can give one away if you decide to buy something on the spur of the moment and they ask for it.