A question about Nema 17 stepper motors

I have a quick question about the Nema-17 stepper motor. I have it wired to an Arduino Uno trying to get both steppers to rotate at the same time depending on how far a sensor senses an obstacle. I have the code uploaded to the Arduino and I have it run off of a 5V battery pack while most everything else is wired to the Arduino and the breadboard. My question is as follows. When I power the program through the Arduino, only one of the steppers will move. I do know that one stepper will not activate until the other stepper finishes its rotation pattern. Is there some way I can wire the wires to make both activate at the same time. Or is it more of an issue with the coding. When I turn on the steppers you can tell one is recieving power so that is why I was confused.

Have a look at stepper motor basics.
Don't try to power any motor from an Arduino board - you will likely damage the Arduino.

Post a link to the datasheet for you stepper motors.
What stepper motor driver boards are you using?

Post your code.

...R

Powering the Arduino from the same supply as a motor will always be problematical,
avoid the whole issue.

What kind of motor (current and winding resistance, number of wires)?