unfortunately a model like that does not exist. The easiest approach is to use 2 seperate machines and link their shafts. However, this isn't quite accurate as it doesn't model the combined flux correctly, but it gives you a starting point.
Building your model in simscape is straight forward, but requires you to use the simscape language which might be a bit of a learning curve: https://www.mathworks.com/help/simscape/lang/creating-custom-components.html
The real challenge is do you know how to model a single winding machine? If you already can do that, then creating a double winding machine should be fairly straight forward as you simply put both set's of equations into the component, but instead of calculating 2 seperate fluxes, you use a shared flux (so both windings see the same magnetic fields and contribute to the same magnetic fields). Similarly, they both use the same shaft and apply torque to the same shaft. The currents and windings however, are completely seperate. Fortunately, most of this works with superposition and is not that hard to model, but it is still going to be a fairly time intensive process if you've never done it before. The main issue is to get the individual contributions to flux correct. Once you know flux, you use it the same way you would in a single winding machine. This would give you a lumped parameter equivalent. It would lack the accuracy of a 3d model in a CAD tool that can do FEA.
