Deduplication of accounting requests

[apopov at cybervisiontech.com]

>From RFC: "The RADIUS server can detect a duplicate request if
      it has the same client source IP address and source UDP port and
      Identifier within a short span of time." 

Does it mean, if my application send accounting requests from one port, I can send only 256 request in short span of time, next request will be handled as duplicate regardless of attributes in it? 
How freeradius detect that package is duplicated? What fields used for this purposes ? Where and how it configured? 


Thanks, 
--Artem