If it's a shield like http://droboticsonline.com/ebaydownloads/L298_Motor_Shield_Manual.pdf
it looks the same, stacking on top of each other and using the same pins will indeed cause problems.
You could connect the E1-M1-E2-M2 pins of one shield to different pins on the arduino though.
In your sketch you'll need use those new pin numbers and name variables like E3-M3-E4-M4 to talk to the second shield. Don't forget to connect ground, +5 for the circuitry and of course power supply.
The problem of servos not responding can be found in one of the delays you're using.
After doing something with motor-shield you programmed a delay(4000).
During that delay Arduino does nothing but waiting for 4 seconds. It doesn't update the readings of the pots attached.
You should check http://arduino.cc/en/Tutorial/BlinkWithoutDelay
(you can also find it in the digital part of examples). It gives you the possibility to perform tasks at a certain moment instead of
just waiting till it's time. That gives you the possibility to do loads of things in the meanwhile.
By the way, Lol, I'll check my girlfriend this evening to see whether she can knipper her kut that fast