Re: Double Pedals that can be used as singles - compiling a list?
My old Pearl P-100 has the same arrangement as the Yamaha. Everything is there in terms of the casting but the parts to attach the hoop clamp are missing from the slave pedal.
It's a very common manufacturing method. The basic tooling for the single model is used for the slave pedal and a separate and new tooling is made for the master. This saves the company a lot of money for manufacturing (only requiring two sets of tooling for both single and double pedals, rather than three in total). In theory it makes it easier to convert most double pedals to singles but some modification is required, as Sjorgras points out.
To convert my slave pedal to a single (not that I use my double any more) would require a hoop clamp and to drill some holes, as well as moving a few fixtures over from the master. It's not a huge amount of work but buying a separate hoop clamp would be difficult and relatively expensive.