Hello,
Yes you can install as many SEPMs as you want as _Brian mentioned above. You can input your license on both of your SEPM server.
Note: Client & license count would not be merge on your status since you will be using two separate SEPM server. You just need to monitor your client licenses on both of your SEPM server to not exceed on 400.
Checking licensing status:
http://www.symantec.com/docs/HOWTO80793
Best Regards,