% of Volunteers who were EV and CM that participated in multiple programs

I have sample data I want to use for a bigger data set. In the data, I have two sheets that have IDs and the different programs these volunteers participated in. The IDs for a volunteer in both sheets represent the same person. I want to find a formula that will find which employee IDs are found in both data sets and then find out which of these employees were in more than 1 program. If an employee was in one program multiple times, then they are not considered to be in multiple programs. I want to find out the percentage of volunteers that were both coaches/mentors and event volunteers and participated in more than one program.