In the Blu Neo phone, why do I have 2 sim cards? What is the 2nd one for?

[AC Question]

in the blu neo phone, why 2 sim cards? what is the 2nd one for?

i got a blu neo 4.5 phone and it asks foe the 2nd sim card to be installed every time i turn it on. do i need it to run the phone? i can make calls and text now without it but i cant use data.