I have 3 RFID readers hanging off a PAHub. I'm getting the RFID UIDs off the readers and storing them in a variable in the Loop. All good so far. I write them to variables RFIDZERO, RFIDONE and RFIDTWO (I was using other names, but thought it might have been getting confused with the other variable names).

Inside the do loops, RFIDZERO and RFIDONE get set to their correct values from the RFID tags. Immediately outside the do loop, I print them again and now, RFIDONE is equal to RFIDZERO's value. No other assignment operators or operation has taken place. WTF?

import M5
from M5 import *
from module import Module4In8Out
from hardware import I2C
from hardware import Pin
from unit import PAHUBUnit
from unit import RFIDUnit



module_4in8out_0 = None
i2c0 = None
file_0 = None
pahub_0 = None
rfid_0 = None
rfid_1 = None
rfid_2 = None


RFIDZERO = None
WritingRFIDs = None
RFIDONE = None
RFIDTWO = None


def btnA_wasClicked_event(state):
  global module_4in8out_0, i2c0, file_0, pahub_0, rfid_0, rfid_1, rfid_2, RFIDZERO, WritingRFIDs, RFIDONE, RFIDTWO
  WritingRFIDs = True


def setup():
  global module_4in8out_0, i2c0, file_0, pahub_0, rfid_0, rfid_1, rfid_2, RFIDZERO, WritingRFIDs, RFIDONE, RFIDTWO

  M5.begin()
  Widgets.fillScreen(0x222222)

  BtnA.setCallback(type=BtnA.CB_TYPE.WAS_CLICKED, cb=btnA_wasClicked_event)

  module_4in8out_0 = Module4In8Out(address=0x45)
  i2c0 = I2C(0, scl=Pin(33), sda=Pin(32), freq=100000)
  pahub_0 = PAHUBUnit(i2c=i2c0, channel=0)
  rfid_2 = RFIDUnit(PAHUBUnit(i2c=i2c0, channel=2))
  rfid_1 = RFIDUnit(PAHUBUnit(i2c=i2c0, channel=1))
  rfid_0 = RFIDUnit(PAHUBUnit(i2c=i2c0, channel=0))
  WritingRFIDs = False


def loop():
  global module_4in8out_0, i2c0, file_0, pahub_0, rfid_0, rfid_1, rfid_2, RFIDZERO, WritingRFIDs, RFIDONE, RFIDTWO
  M5.update()
  if not WritingRFIDs:
    if rfid_0.is_new_card_present():
      RFIDZERO = rfid_0.read_card_uid()
      print((str('RFID_0: ') + str(RFIDZERO)))
      rfid_0.close()
    if rfid_1.is_new_card_present():
      RFIDONE = rfid_1.read_card_uid()
      print((str('RFID_1: ') + str(RFIDONE)))
      rfid_1.close()
    if rfid_2.is_new_card_present():
      RFIDTWO = rfid_2.read_card_uid()
      print((str('RFID_2: ') + str(RFIDTWO)))
      rfid_2.close()
    print((str('RFID_0: ') + str(RFIDZERO)))
    print((str('RFID_1: ') + str(RFIDONE)))
    print((str('RFID_2: ') + str(RFIDTWO)))
  else:
    file_0 = open('/flash/rfidtags.txt', 'w')
    file_0.write(RFIDZERO)
    file_0.write('\r\n')
    file_0.write(RFIDONE)
    file_0.close()
    WritingRFIDs = False
    print('Wrote the file')


if __name__ == '__main__':
  try:
    setup()
    while True:
      loop()
  except (Exception, KeyboardInterrupt) as e:
    try:
      from utility import print_error_msg
      print_error_msg(e)
    except ImportError:
      print("please update to latest firmware")