Two sites but only have one Security Certificate

What is typical scenario for when you have a site in development, and then one that is in production (live / published) and they both need a Security Certificate, but there is only one? I am new to this…

That is the scenario right now for my client. i'm trying to troubleshoot and test out these payment modules and they seem somewhat disconnected. The SSL is turned on but there is no Security Certificate in place and i cant tell if that is causing problems or not?,

Any advice or discussion on this would be very helpful. my client is not using a commercial host provider which means i have no tech support to help w/ this.

You'll want to install your client's test site in a sub-directory (or folder) of the client's main site. That way the SSL certificate "propagates" down the chain.

So, if your client's site is clientsite.com you want to install the test version in clientsite.com/test

ok, good answer. thank you