It depends on the CA and the certificate license. To install the same certificate on multiple servers, first install the certificate files to the server where the CSR was originally generated. Then import the files (along with the private key) to the respective servers. This way, your servers will each have a copy of the certificate with its private key installed on it. Since this process involves copying the private key into the servers, it has to be done very carefully in a way the private key is not exposed. The key can be copied through SSH commands, or it may be packed with the certificate into a PKCS#12 archive (aka “PFX file”) with password-based encryption: this will give decent protection for the key while it transits between the two servers if the password is random enough.