SSL certificate on SPP appliances

referred to the KB How to generate and install a SSL web certificate from a Safeguard created "Web Certificate Request" (294210) (oneidentity.com) i am asking to create an SSL certificate in order to secure the communication with the appliances and not to have the pop up on the SSL/TLS certificate appear. The only doubt is: do I ask for a single CSR and have a single certificate sent to me which I will then upload in safeguard and distribute on the other two appliances? Or do I have to create 3 CSRs for 3 certificates since there are 3 appliances?