In SQL Server and using only client side encryption requests, can I use a different certificate for each client?
SQL Server SSL encryption that is initiated from the server does not require that the client have a copy of the certificate in advance. The certificate and private key are stored in the certificate store of the service account on the server. If the certificate is selected using SQL Server Configuration Manager and Force Encryption is set to true, then whenever a client requests a session, the server replies with the encryption requirement and sends a copy of the certificate, which contains the public key. To establish an SSL or TLS session, the client randomly selects a symmetric session key and transmits it back to the server encrypted by the public key. This random key is then used as the basis for secure communication. It is recommended to use a domain certificate or CA certificate and not a self signed certificate as a self signed certificate would leave you vulnerable to a man in the middle attack. 

There is also a way to request from the SQL Server Management Studio client that a session be encrypted. I don't see any certificate configuration, so it may use a self signed certificate generated at the client to initiate a secure connection. Either way, you can see if any connections are encrypted using the sql statement:

    select encrypt_option, * from sys.dm_exec_connections