I finally figured it out after a couple hours. You must first create a new agent, go through setup like normal. Add your knowledge base and logo and everything. Configure settings like generative orchestration on/off, authentication, etc. Then you need to open the solutions page and in the lefthand vertical tool bar navigate to library where you need to make a component collection. Only choose the developer-added custom topics and flows. If you include all topics in your collection, once you add it to your new (duplicate) agent, there will be two of all of the system-generated default topics. Once you have your collection, click into it and there is a large box in the top right that lets you add an existing agent. Once you select the new (duplicate) agent to the collection, navigate back to the copilot studio UI and click into the duplicate agent where you'll see all your topics populated instantly.

Hope this helps someone else!