Saving Synced Files For Later Use

If you created a sequence, in the timeline panel, that's it's own thing. It shows in the Project panel as a sequence separate from any clips used. Change the name maybe so it's easier to see it's not a clip, as the name assigned will be the first clip added.

But sequences have different icons in the Project panel. So that tells you what's what.

So just close the sequence and drag the other clip to the blank timeline panel ... or right click/create sequence from clip.