The latest Kurzweil pro products like the PC4 or the SP6 have two 1/4 inch stereo jacks for switch pedals. This means that you can have up to 4 switch pedals. This is very helpful for people that want to do something more than triggering sustain and sostenuto with the pedals, like changing your multi or triggering chords. The possibilities are endless.
But Kurzweil does not sell a double pedal at this moment, so, how do I get these 4 pedals?
Well, you can buy one that is compatible like the Studiologic VPF2/10B.
But be careful when buying this one because there are 4 models and you want the one with the stereo connector, not the one with the 2 separate connectors. While the 15B might work I personally have not tried it so I will recommend the 10B that I have and works well.
The other option you have is to use regular single pedals thru an adapter. While the adapter will have one 1/4 inch stereo male connector on one end and two 1/4 inch mono female connectors on the other end be careful because they sell a lot of adapters that look exactly the same but the 2 female connectors are stereo. Make sure you buy the one with the female mono.
With either solution you should be all set to use the 4 pedals.