RC522 not working with multiple tags

Hello. I hope I'm posting in the appropriate forum.

I want to use a RC522 module to check the presence of two tags that are in the module's proximity. Since it has anticollision, I thought reading the tags in an infinite loop and comparing the UIDs with the ones that I expect should do the trick. But it only works with one tag. I expected two or more tags to show up one by one, but instead if I put two tags close to each other, none of them shows up. By placing the tags a few millimeters away from each other and from the module there is a certain spot where the module works as I want it to do. But even the slightest change in distance between the tags or between one tag and the module will cause either one or none of them to get read.

I used this library https://github.com/miguelbalboa/rfid and I did the first tests with its example called DumpInfo.

I'm willing to use any other module that could accomplish the same task, on 125 kHz or 13.56 MHz. The problem here is that most modules are used for authentication and they only read the tag once, as it enters the field.

Any suggestions? I have no idea if it's a software issue or a hardware issue and that's why I got stuck.