Cloning a VM is equivalent to deploying VM from template. Here as well you get option to customize guest OS. To clone VM, simply right click VM, say clone this VM. In order to enable Guest OS customization.

In order to enable guest OS customization, you need to configure Virtual center. Download latest sysprep tool from Microsoft, this customization applies only for Windows,for Linux it is inbuilt. Launch the installer and extract the contents to C:\Documents and Settings\All Users\Application Data\Vmware\VMware VirtualCenter\sysprep1.1

Some folders as per OS configuration are already created under this folder, extract them into respective folders.

Guest OS customization would look like

1) Enter Name and Organization

2) Guest OS Name, you have various option to select from, Select as per your organization's policy

3) Enter Product ID and License information

4) Enter Administrator Password, also in the same screen if you would like Admin to logon and how many times, you select.

5) Pick up appropriate time zone

6) Run once keep default

7) Workgroup or domain select as per your organization policy

8) Operating system options

Generate SID's

Delete all user accounts

9) In the end you have option to save customization for later use and it finishes OS customization part.

http://pubs.vmware.com/vi301/wwhelp/wwhimpl/js/html/wwhelp.htm