once lease per client is not working

[VKR V]

I have configured one-lease-per-client under class definition. My windows machine always gets the same IP even after expiry of lease time (renewal happens on the same IP) or IP address is release (windows machine makes request for the same iP in DISCOVER packet) or machine is booted up after power cycle.
   
  Also, deny duplicates apparatently not working :( 
   
  authoritative;
deny duplicates;
deny bootp;
ignore declines;
ping-check true;
option domain-name-servers 10.20.20.1, 10.20.20.2;
default-lease-time 7200;
max-lease-time 7300;
class "private-pc" {
   match if substring(option host-name, 0, 4) = "TEST";
   one-lease-per-client on;
}
   
  Any clue?
   
  VK

 
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