In this help doc

A scene can have up to two avatars that talk to each other in turns. This doc gives the short answer. For step-by-step instructions, including how to write the conversation, set each speaker's voice, swap an avatar, and preview, see Create a Dual-Avatar Conversation Scene.

To add a second avatar to a scene, open the video editor and click the Conversation tab (the two-person icon) at the top of the script panel on the right.

A second avatar joins the scene. The script now shows one turn for each avatar, with + Add Pause between them.

💡 Tip: To start with a ready-made two-avatar conversation, click Dual Avatar in the banner at the top of the dashboard.

How many avatars can I add to one scene?
Up to two.

Can the avatars talk at the same time?
No. They take turns in the order of the script.

How do I replace one of the avatars?
Click the avatar on the canvas, then choose a new one in the Avatar panel. See Create a Dual-Avatar Conversation Scene for the steps.