Two videos running at once
A duet on TikTok records a new video that plays alongside an existing public post, both running at the same time in a split frame. The original keeps its audio and its half of the screen throughout, which is the detail brands underestimate: your product is competing for a quarter of the visible frame, so duets are good for reaction and personality and poor for showing anything in close detail.
Because both halves play together, the form is reactive by nature. You are watching somebody watch something, and the performance is all timing: laughing on the right beat, pointing at the claim as it is made, pulling a face when the original oversells. Layout options and availability have changed across app versions, so confirm the current behaviour in the platform's documentation.
That parallel structure is what separates it from a TikTok stitch, which lifts a fragment and then takes the screen over completely. A duet never takes over. The source stays visible to the last frame, and the original creator keeps credit and attention for the whole runtime.
What a duet gets a brand
Two useful shapes. A creator duets your own post and endorses it, which reads as a second opinion rather than a second advert. Or a creator duets somebody else's video and your product enters as the answer, which is a cheap way to respond to a category claim without producing the setup yourself.
Both shapes share one hard limit for paid media: half the screen belongs to somebody you have no agreement with. You cannot license what you did not make, so these generally stay on organic channels. When one performs, remake the good half as a standalone vertical ad instead of trying to spend behind a split screen.
Briefing the reaction side
Tell the creator which post to duet, which beat to react on, and what to say at the end. The temptation is to let them freewheel for thirty seconds, but the better output usually has one clear reaction moment and one plain sentence of conclusion. Frame their half tight so they stay readable at quarter size.
Check two things before the brief goes out. The source post has to allow duets, and the account behind it should not be a competitor or a controversy you would rather avoid, which is a quick brand safety pass. Decide as well whether the clip stays organic or whether you will pay to reshoot it, and write that into the statement of work.
How it's used
The duet on our launch post outperformed the launch post itself, which says the second-opinion angle works. Let us get three more creators doing the same thing this month.
Ask for the duet: react at the moment she says it never works on curly hair, then one sentence at the end about what you use instead.