I don’t think you can, but perhaps the opposite might be possible:
“Opaque IDs persist across all channels, and they do not change unless the viewer explicitly requests to rotate his identity. Developers are encouraged to use their EBS to store per-viewer information, using opaque IDs as keys. If your extension needs to know the viewer’s numeric Twitch ID, check the box under Request Identity Link in the extension’s Extension Capabilities section. Once the viewer accepts your request to share his Twitch identity, his numeric Twitch ID is provided in the Extension Helper’s onAuthorized() callback function.”
So maybe you can use this to link them? Hope it helps