I am currently using a rfid rc522 nfc tag reader with raspberry pi using the MFRC522-python code. In my project I need to collect data from two rfid rc522 cards at the same time, rc522 are located at two different places and I want to distinguish between them, I mean how can I tell the pi which card has detected the tag.
Your rc522 reader has "CS" pin which can be controlled to activate each rc522 reader. You can try to toggle them one by one to be able to read the individual one.
The MFRC522-python module does not seem to allow to control/specify it, so you may need to modify the module or control GPIO pin yourself: that's line 113 in https://github.com/mxgxw/MFRC522-python/blob/master/MFRC522.py.
I have a solution using Raspberry Pi at this link: https://github.com/erivandoramos/TwoRC522RPi