2 motors controlled by one joystick

Below is some pot test code. You might make something similar using "while" loops to trap the input of one of the pots while it is not centered, excluding any control input from the other pot. That should prevent control conflicts between forward/reverse and clockwise/counterclockwise servo operation.

//zoomkat dual pot/servo test 12-29-12
//view output using the serial monitor

#include <Servo.h> 
Servo myservo1;
Servo myservo2;

int potpin1 = 0;  //analog input pin A0
int potpin2 = 1;

int newval1, oldval1;
int newval2, oldval2;

void setup() 
{
  Serial.begin(9600);  
  myservo1.attach(2);  
  myservo2.attach(3);
  Serial.println("testing dual pot servo");  
}

void loop() 
{ 
  newval1 = analogRead(potpin1);           
  newval1 = map(newval1, 0, 1023, 0, 1; 
  if (newval1 < (oldval1-2) || newval1 > (oldval1+2)){  
    myservo1.write(newval1);
    Serial.print("1- ");
    Serial.println(newval1);
    oldval1=newval1;
  }

  newval2 = analogRead(potpin2);
  newval2 = map(newval2, 0, 1023, 0, 179);
  if (newval2 < (oldval2-2) || newval2 > (oldval2+2)){  
    myservo2.write(newval2);
    Serial.print("2- ");    
    Serial.println(newval2);
    oldval2=newval2;
  }
  delay(50);
}