SAP SSL one cert - multiple systems - same domain

Hello - not able to find an answer to this question so wondering if I can get a quick answer..

Can we use one CA signed SSL certificate for mutliple systems (Portal, ECC, etc) in the same domain? Does SAP support this?

Also, our ECC system is referenced externally by a different URL and internally by its hostname. Do we need to generate two different certs for the ECC system (one for the internet URL and the other for hostname)?