In BioStar 1, when you read a EM card, the custom ID (facility code) is read as well.
If you prefer to not read the custom ID at all you can configure as below.
Normal CSN read has card ID of 31376.
Configure Card ID format in Format Type in Operation to Wiegand:
Create custom Wiegand format with all ID bits.
Now when the card is read I only get the card ID bit and no custom ID bit.