If you can see full EXIF info including Tv and Av, then only a single exposure was used. Of course a single 14-bit RAW file can contain as much dynamic range as a -3, 0, +3 jpeg series. Most HDR software will allow you to tone map a single image and the result will look like it has been "HDRed".

Strictly speaking, *High Dynamic Range* imaging can be defined much broader than the 32-bit floating point digital image tone mapped to fit in 8 bits that we refer to as HDR today. The first known instance of combining different parts of two exposures, one light and one dark, to produce a single print of a seascape was in 1850. The dodging and burning that Ansel Adams raised to an art form was a method to coax all of the higher dynamic range  available in the negative to the less capable print. Many have used layers in Photoshop and other imaging programs to combine the lighter elements of a dark exposure and the darker elements of a light exposure to produce a lower contrast image that contains dark foregrounds with bright skies. Others have taken a single RAW file, produced several images from it at varying exposure levels and then combined them using layers in the same way. The next hot buzz word, *Exposure Fusion*, is just another form of HDR imaging.

**There is nothing inherent in HDR processing that allows recovery of blown highlights.** If the highlights are clipped in the RAW data, they are gone and the information no longer exists to recover them. If, on the other hand, the highlights appear clipped in the jpeg thumbnail or preview 8-bit rendering of the RAW file, the actual file may still contain the information needed to recover them. **If images are taken at longer shutter speeds and wider apertures than the lighting would normally indicate without clipping the highlights, some form of density filter needs  to be used.**