how to attach to a TAP interface from two different processes

Question

I have a tap interface created like this:

ip tuntap add dev tap0 mode tap user myusername
ip link set tap0 up

I then attach to tap0 using python and another program written in C++

Python:

def tapAlloc(tapname, mode):
    tap = os.open('/dev/net/tun', mode | os.O_NONBLOCK)
    ifr = struct.pack('16sH', tapname, IFF_TAP | IFF_NO_PI)
    fcntl.ioctl(tap, TUNSETIFF, ifr)
    return tap

(Just for simulation) if I try to attach to tap0 twice:

f1 = tapAlloc('tap0', os.O_RDWR) 
f2 = tapAlloc('tap0', os.O_RDWR) 

I get the error when I run this for f2:

fcntl.ioctl(tap, TUNSETIFF, ifr)
IOError: [Errno 16] Device or resource busy 

How can I attach to a tap interface from multiple processes ?