Omnibot Michelle--Ultrasonic sensors

So during this quarantine period I began working on a pet project to make a robot companion. I didn't wish for it to be WiFi or keyboard controlled--fully autonomous and able to navigate for itself. So far I have been really successful in some code I have cobbled together. I am suing Python, so that may be why. I am using the original gearbox and motors the Omnibot came with from 1982, and they work great with the L298D motor controller that I am using. Just tonight I reworked the ultrasonic sensors, the HC-SR04, the typical ones that are cheap an easy to come by, and that had success seeing that when their is less than 15cm to go, it will stop, back up, turn a direction and carry on. I would leave well enough alone and carry on myself to a new piece of the robot to install and make, however, in the code I was trying to work out a rear senors, or a second HC-SR04, but I am not have the best of luck understanding where I am going wrong with this:

import RPi.GPIO as GPIO                    #Import GPIO library
import time


#Import time library
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)                    # programming the GPIO by BCM pin numbers


TRIG = 17
ECHO = 27
TRIG1 = 23
ECHO1 = 24
led = 22


m11=16
m12=12
m21=21
m22=20


GPIO.setup(TRIG,GPIO.OUT)                  # initialize GPIO Pin as outputs
GPIO.setup(ECHO,GPIO.IN)                   # initialize GPIO Pin as input
GPIO.setup(TRIG1,GPIO.OUT)                  # initialize GPIO Pin as outputs
GPIO.setup(ECHO1,GPIO.IN)                   # initialize GPIO Pin as input


GPIO.setup(led,GPIO.OUT)                  


GPIO.setup(m11,GPIO.OUT)
GPIO.setup(m12,GPIO.OUT)
GPIO.setup(m21,GPIO.OUT)
GPIO.setup(m22,GPIO.OUT)


GPIO.output(led, 1)


time.sleep(5)


def stop():
    print "stop"
    GPIO.output(m11, 0)
    GPIO.output(m12, 0)
    GPIO.output(m21, 0)
    GPIO.output(m22, 0)


def forward():
    GPIO.output(m11, 1)
    GPIO.output(m12, 0)
    GPIO.output(m21, 1)
    GPIO.output(m22, 0)
    print "Forward"


def back():
    GPIO.output(m11, 0)
    GPIO.output(m12, 1)
    GPIO.output(m21, 0)
    GPIO.output(m22, 1)
    print "back"


def left():
    GPIO.output(m11, 0)
    GPIO.output(m12, 0)
    GPIO.output(m21, 1)
    GPIO.output(m22, 0)
    print "left"


def right():
    GPIO.output(m11, 1)
    GPIO.output(m12, 0)
    GPIO.output(m21, 0)
    GPIO.output(m22, 0)
    print "right"


stop()
count=0
while True:
 i=0
 avgDistance=0
 for i in range(5):
  GPIO.output(TRIG, False)                 #Set TRIG as LOW
  time.sleep(0.1)                                   #Delay


  GPIO.output(TRIG, True)                  #Set TRIG as HIGH
  time.sleep(0.00001)                           #Delay of 0.00001 seconds
  GPIO.output(TRIG, False)                 #Set TRIG as LOW


  while GPIO.input(ECHO)==0:              #Check whether the ECHO is LOW
       GPIO.output(led, False)             
  pulse_start = time.time()


  while GPIO.input(ECHO)==1:              #Check whether the ECHO is HIGH
       GPIO.output(led, False) 
  pulse_end = time.time()
  pulse_duration = pulse_end - pulse_start #time to get back the pulse to sensor


  distance = pulse_duration * 17150        #Multiply pulse duration by 17150 (34300/2) to get distance
  distance = round(distance,2)                 #Round to two decimal points
  avgDistance=avgDistance+distance


while True:
 i=0
 avgDistance=0
 for i in range(5):
  GPIO.output(TRIG1, False)
  time.sleep(0.1)


  GPIO.output(TRIG1, True)
  time.sleep(0.00001)
  GPIO.output(TRIG1, False)


 while GPIO.input(ECHO1)==0:
      GPIO.output(led, False)
 pulse_start = time.time()


 while GPIO.input(ECHO1)==1:
      GPIO.output(led, False)
 pulse_end = time.time()
 pulse_duration = pulse_end - pulse_start
 distance = pulse_duration * 17150
 distance = round(distance,2)
 avgDistance=avgDistance+distance 




 avgDistance=avgDistance/5
 print avgDistance
 flag=0
 if avgDistance < 15:      #Check whether the distance is within 15 cm range
    count=count+1
    stop()
    time.sleep(1)
    back()
    time.sleep(1.5)
    if (count%3 ==1) & (flag==0):
     right()
     flag=1
    else:
     left()
     flag=0
    time.sleep(1.5)
    stop()
    time.sleep(1)
 else:
    forward()
    flag=0

Since I ran this, it just comes to the stop command and just waits.....maybe I got some kind of logic conflict or dual TRIG and ECHO; I had figured what I wrote out from both sensors was correct but I guess not. Any answers or recommendations how to get two sensors working for front and rear ends of this robot?