No, a certificate must be used only on one server. However, there are certain certificates which may be used on several servers or you can buy multiple licenses for the same certificate to be used on more than one server; for example: SSL SAN Certificates. To secure multiple host names for the same domain and server, there is an option of a Wildcard SSL Certificate. E.g.: webmail.yourdomain.com, intranet.yourdomain.com and www.yourdomain.com).