Server 2008 R2 IP conflict on devices

good morning SpiceHeads,

lately we been having problem with our DC 2008 R2 . the problem is that dhcp assigns IP to Devices but a few of them don't show on DHCP Scope i.e 10.1.x.x so other devices are beeing assign the same ip and is conflicting.

1.we restarted DHCP services. didn't help.

2. we Reconsile those Ip and they still show up

3. we we exlcuding those IP from being assign but now is about 20+ devices conflicting.

any suggestions on this guys please

thank you very much for your time.