This is most likely motion blur from the phone moving during the exposure, not HDR. The clue is that the image isn’t just doubled — there’s also smearing between the main image and the ghost, which is typical of camera shake during a relatively slow shutter speed, especially indoors.

From a single photo, there usually isn’t a perfect fix. Your options are:

• manually retouch parts of the image if the subject is simple,
• try deconvolution or motion-blur reduction software, which can sometimes improve it,
• but in most cases the best solution is to re-shoot.

To avoid it next time:

• hold the phone more steadily,
• avoid jabbing the shutter button,
• use more light if possible,
• stabilize the phone or support it on something solid.

So: the cause is camera movement during exposure, and while software may help a little, a clean correction from one image is usually not possible.