That's a really cool and creative idea to come out from IG. It's been a while since that has happened.

Today, Instagram launches a feature which lets people add multiple music tracks to Reels, allowing elements of the soundtrack to vary in one clip.
Thus, you can now have up to 20 tracks in one Reel, overlapping or merging them into each other to fit the various phases of the clip.

Which technically you can also do in the video editor CapCut, by TikTok but isn't really designed for the same kind of multi-track mixing.

With this functionality, you can DJ, double tracks, mix for all-new versions of songs. Or, you could use it as an abrupt switch-up when your Reel changes focus, or perhaps you could crossover between old and new versions of songs to reflect time passing.

There's all sorts of imaginative ways that this might be leveraged, and is sure to start all manner of new audio trends in the app.

But that's not all: others will also have the ability to use the same audio you've created for their own clips, and users will also be able to view a complete list of tracks that you've added (last two frames above).

It's a good addition, and as noted, an interesting, mostly original concept from an Instagram team that's seemingly gotten the majority of its inspiration from TikTok in recent years.

That is not necessarily a criticism, as TikTok clearly is dialed into the zeitgeist, so it makes sense to replicate it. However it's nice to see IG come up with its fresh take on a key trend, which will no doubt see its own replicants.