There are many types of screw tips beyond the traditional Phillips and flat-head types. Mostly, unusual screw heads are used to prevent tampering as the tools that are compatible with them are uncommon. A screw head with two holes is called a spanner head screw (also known as snake eyes and pig nose screws). They can often be found on golf cleats and in many public toilets.
Pin spanner screws
Pin spanner or spanner screws have two holes in the top of the screw head. The driver or bit that is compatible with them will have two prongs that fit into those holes. Some screw heads will have the holes in the centre, while others have notches at the edge of the screw head.
Finding a driver for spanner screws isn't a simple matter of going to the hardware store. A bit or driver for these screws will have to be special ordered.
Just as traditional screws and screwdrivers come in many sizes, so do spanner screws. If you are looking to remove particular screws, you'll have to make some measurements to be sure you're ordering the correct driver or bit.
When making measurements to determine the proper drive to use with a particular screw, make sure to measure from the outer edges of the holes on the screw head.
Spanner screws are not ideal for jobs that require a lot of force. This is because the relatively delicate prongs on the bit or driver will not withstand an excess amount of torque. While spanner screws are terrific for preventing tampering, and are among the most common security screw type, they are not ideal for boring into dense materials.
In a pinch, given the relatively low torque on a spanner screw, it's sometimes possible to devise your own tool to remove one. Try bending a paper clip or other hardy wire to fit into both holes simultaneously and use pliers as close to the head as possible, applying even pressure as you attempt to loosen the screw.