Yes. A single sensor can capture stereoscopic 3D if the optics split the scene into separate left- and right-eye images on different parts of the sensor.

This is commonly done with 3D lens adapters that mount in front of an existing lens and project two views side by side onto the same sensor. Products like Loreo and Kula 3D have used this approach. There have also been dedicated 3D lenses for video, and systems such as Samsung’s NX 45mm 3D lens used an internal mechanism to alternate or separate the two views across exposures.

The tradeoff is that each eye usually gets only part of the sensor area, so effective resolution per view is reduced compared with using the full sensor for one image. But in principle, yes: one sensor can record stereo information if the optical system creates two distinct viewpoints and maps them onto the sensor.