Unexpected behavior with multiple notifiers #1888

# Do this first to set up two virtual can buses with bidirectional gating:
# sudo modprobe vcan
# sudo ip link add dev vcan0 type vcan
# sudo ip link add dev vcan1 type vcan
# sudo ip link set vcan0 up
# sudo ip link set vcan1 up
# sudo modprobe can-gw
# sudo cangw -A -s vcan0 -d vcan1 -e
# sudo cangw -A -s vcan1 -d vcan0 -e

import can

class NamedPrinter(can.Printer):
    def __init__(self, name: str, *args, **kwargs) -> None:
        self.name = name
        super().__init__(*args, **kwargs)

    def on_message_received(self, msg: can.Message) -> None:
        print(f"Printer {self.name}")
        super().on_message_received(msg)

vbus0 = can.Bus(interface="socketcan", channel="vcan0")
vbus1 = can.Bus(interface="socketcan", channel="vcan1")

not1 = can.Notifier(vbus1, [NamedPrinter("A")])
not2 = can.Notifier(vbus1, [NamedPrinter("B")])

msg = can.Message(arbitration_id=0x11, data=b"hello")

for i in range(4):
    vbus0.send(msg)

# Output:
# Printer A
# Timestamp: 1730815787.280445    ID: 00000011    X Rx                DL:  5    68 65 6c 6c 6f              'hello'    Channel: vcan1
# Printer B
# Timestamp: 1730815787.280519    ID: 00000011    X Rx                DL:  5    68 65 6c 6c 6f              'hello'    Channel: vcan1
# Printer A
# Timestamp: 1730815787.280466    ID: 00000011    X Rx                DL:  5    68 65 6c 6c 6f              'hello'    Channel: vcan1
# Printer B
# Timestamp: 1730815787.280531    ID: 00000011    X Rx                DL:  5    68 65 6c 6c 6f              'hello'    Channel: vcan1