Windows 2003 Server license

I have a Windows Server 2003 R2 Standard Edition running the company email. I would like to install the Windows Server 2003 license on my old (non production) server to test Windows updates before installing the updates on my email server. Please note to get Windows update I will need to connect the “old server” to the company network. I contacted Microsoft Activation center but they were not much help, “One license, one server install, that’s it”. Will I have any problems when connecting the second server to the network?

Thanks