Windows 2000 server cals

We currently have a windows 2000 server SBS which is our domain controller. I may be able to acquire an additional server running windows 2000 server (standard). I have 50 Cals for my existing server (per seat mode) and was wondering if i need to purchase an additional 50 cals for the new server also? If not will my existing 50 users be able to access both servers with my existing batch of 50 cals?

Thanks