RLM_IPPOOL bug?

my radiusd uses rlm_ippool. Sometimes ippool gives one ip for two different users simultaneously. here output of rlm_ippool_tool. # rlm_ippool_tool -va /etc/raddb/pools/db.pool-1-pool1* | grep X.Y.Z.170 NAS:192.168.0.1 port:0xde - ipaddr:X.Y.Z.170 active:1 cli:0 num:1 NAS:192.168.0.1 port:0xad - ipaddr:X.Y.Z.170 active:1 cli:0 num:1