RFID solution for reading multiple tags
In RFiD world, you 3 type of hardware.


The RFiD LF (about 125kHz).
The RFiD HF (13.56MHz).
The RFiD UHF (444MHz or 866MHz band).


If you want to detect multiple tags, you need to have a reader with anticollition protocol.
I recommend using RFiD HF because the antenna design and debug is easier than UHF.
You can use the OMNIKEY multi ISO reader which is a good product.
You can find it on the RFID SHOP website.