SPI1 multiple CS issue

DI1 = MCP23S17.MCP23S17(1, 0, 1000000, "P9_27")
value1 = DI1.readAll()
print "Pre-DI1: ", value1
#OUTPUT: Pre-DI1:  [255, 255, 255, 0, 254, 0, 255, 0, 0, 0, 255, 0, 82, 82, 254, 0, 1, 0, 1, 0, 1, 0, 0, 0]

DI2 = MCP23S17.MCP23S17(1, 1, 1000000, "P9_27")
value2 = DI2.readAll()
print "Pre-DI2: ", value2
#OUTPUT: Pre-DI2:  [255, 255, 255, 0, 254, 0, 255, 0, 0, 0, 255, 0, 82, 82, 254, 0, 0, 0, 0, 0, 0, 0, 0, 0]

# **** This is where the error is happening ****
value1 = DI1.readAll()
print "Post-DI1: ", value1
#OUTPUT: Post-DI1:  [255, 255, 255, 255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 255, 0, 0, 0]

value2 = DI2.readAll()
print "Post-DI2: ", value2
#OUTPUT: Post-DI2:  [255, 255, 255, 0, 254, 0, 255, 0, 0, 0, 255, 0, 82, 82, 254, 0, 0, 0, 0, 0, 0, 0, 0, 0]

class MCP23S17(object):
    """MCP23S17 I/O Expander"""

    def __init__(self, bus, device, speed, reset_pin):
        """Initialize the MCP Expander"""

        self.bus = bus
        self.device = device
        self.reset_pin = reset_pin
        self.speed = speed

        self._device = SPI(self.bus, self.device)
        self._device.open(self.bus, self.device)
        self.reset()

        # Set up attributes
        self._device.cshigh = False  # active Low cs
        self._device.lsbfirst = False  # MSB first
        self._device.mode = 0b00  # mode [CPOL|CPHA]
        self._device.msh = self.speed  # speed
        self._device.threewire = False  # SI/SO signals are not shared
        self._device.loop = False # Not in a loopback configuration

        self.setup_chip()

def setup_chip(self, IOCON_CONFIG=IOCON_CONFIG):
        """Set up the IOCONFIG Register"""
        self.writeU8(IOCON, IOCON_CONFIG)

def readAll(self):
        """Read all registers"""
        values = self._device.xfer2([OPCODER,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0])
        return values

#Configure IOCON here:
IOCON_CONFIG = 0b00000000
#IOCON_CONFIG |= BANK_1       # If using this feature, define bank = 1
IOCON_CONFIG |= MIRROR_ON
#IOCON_CONFIG |= SEQOP_DISABLE
IOCON_CONFIG |= DISSLW_DISABLE
#IOCON_CONFIG |= HAEN         # Uncomment to enable hardware addressable
#IOCON_CONFIG |= ODR
IOCON_CONFIG |= INTPOL