Unexpected submitted order

Hi everyone,
I’m using Alpaca python library (https://github.com/alpacahq/alpaca-trade-api-python).
I’m running some tests on the Paper Trading account.

As you can see in the log.txt I’ve submitted only one order for NFLX for 11 stocks, but I’ve received two execution messages with two different order ids (for a total of 22 stocks instead of 11 stocks):
‘id’: ‘e8b8fb43-9680-4a5f-98d4-520b8aa2f6b3’
‘id’: ‘c043502e-0b41-449d-9648-cac45a7c2c93’

I have only called the submit order API once with Market type order.

The submit order has been sent using REST api, while the order information are received using the StreamConn registered on ‘trade_updates’ channel (BusDelBroker\AlpacabusSrvBrokerAlpaca.py).

Here you could find the code and the log.txt: https://drive.google.com/file/d/1Kp3UhsNcjyOCBj04_liLV13X68qw0eHo/view?usp=sharing