Yes, the 2" Receiver Adapter is designed to also be useful as a single tine spear. Adapters are available to mount a spear in a 2" receiver hitch. The gussets of the adapter provide anti rotation of the bale. The best method of use is to curl the bale all the way back and lift up a bit to get the weight on the receiver adapter.
I've long considered adding some features for adding more spears, but the demand hasn't been high enough. For the sizes of most of the tractors being used, a single spear really seems adequate.