So it could be a solution to build my own Tags, wich I can read then.
I've found these articles. As I understand the word "spoofing" it actually means they are selfmade Tags.
http://wiki.smallroom.net/doku.php?id=terd:projects:rfidspoofer
With these it should be possible to implement an algorithm wich makes sure only one tag is readable at the time.
Do I get it right?