Win 2008 R2 Duplicate DHCP Hostnames Leases. Same workstation gets 2 leases

This is kind of an old post, but it still comes up in search results, so I'm going to add to it.

First: having two DHCP servers in a subnet is not going to cause problems no matter what, that's a very misleading statement. What will cause issues is two DHCP servers which are offering the same pool of addresses. You can have two servers offering different ranges of IP addresses (like 192.168.1.1-100 on one and .101-200 on a second) within the same subnet without causing any issues at all. In fact, if you want to have redundant DHCP in your network, this is a recommended/best practice way to do it.

Second, here's some instructions from Microsoft which may get someone a little closer if they happen to have a similar issue: http://technet.microsoft.com/en-us/library/ee405264(v=ws.10).aspx

You should consider replacing the DHCP server, as it is obviously broken. DHCP servers should keep lease information between restarts and preferably also probe addresses before releasing them into the pool to avoid address duplication.

If that is not an option you can drop the lease length. As long as the DHCP server can handle the churn it should work, but short leases will cause a small increase the amount of broadcast traffic on your network.

Short leases are primarily a problem when you have clients disconnecting and reconnecting a lot, for example in WiFi networks. Very short leases (less than 1 minute) can cause weird problems with some DHCP clients that have time-outs longer than the lease.