Unexpected behaviour with `update_image`

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](https://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](https://www.open3d.org/docs/release/) and the [latest documentation](https://www.open3d.org/docs/latest/) (for `main` branch).

### My Question

Hi, just thought I would flag a GUI bug with update_image that will replace all the images that are the same within the layout context. A work around it to slightly modify each image but just thought I would flag it and help others if they have similar issues.