Duplicating a Class is like adding a new Class to a Program. In other words, all you are doing is copying the shell of the Class (no Enrollments go with the Class), which are the settings:
To duplicate a Class into one or more Programs, follow these steps:
Step 1 - Duplicate Classes Button
Head to Classes on the left sidebar. Click on Duplicate Classes at the top.
Step 2 - Select Classes
Select the Class(es) you wish to duplicate, either by selecting them one-by-one or by selecting all. Then click Duplicate.
Step 3 - Copy into Program
This new window will show how many Classes you are duplicating (see below). Click the Program on the right side to which you want to copy the Class, then click Confirm.
You can only click on one Program in this window; to copy the same Classes into more Programs, click the Duplicate button to go through the process as many times as needed.
You may notice a switch at the top called "Change Program." If switched on (like the image below), any Programs with an Enrollment end date in the past will show.