L293 question

I am controlling 2 dc motors with arduino through an L293... when both motors are moving fwd the have the same speed but if i stop the one the speed of the other increases..

is this normal?

nope! try changing the power supply

is this normal?

It is if the power supply can't supply enough current to drive both motors. Shutting one off reduces the current demand, so the other motor then runs properly. As newbie says, try changing the power supply, or tell us something about it and the motors.

thank you for your replies