I got a question in my workshop yesterday from a student who has been invited to speak at two different banquets for two different groups of people, and he wondered if he could use the same material for both.
We never want to give a canned speech; that is, a speech that you wrote once and continue to deliver exactly the same as it was written to every group you speak to. However, having good base content that you can tweak and customize is a great idea.
Most of us who speak on a regular basis have a couple of standard topics we speak on. There's no need to reinvent the wheel each time we go out. However, it's important to learn about the groups you're speaking to so you can make sure your content is applicable to them and fits their culture, needs and interests.
So yes, use the same speech or presentation, but make sure that you're taking the time to tailor it to each group with specific references, personalized humor, and appropriate exercises and activities.