I cannot think of an easy way to get the two formulas into a single window like this report, but there is a way to get the two models. First, I think fitting a single model is the way to go, but to get the report the way you want do this: When you are fitting your model put the categorical variable in the BY role rather than in the model. This will give you two separate models, one for each level of the categorical variable. Then, for each level, go to Estimates > Show Prediction Expression to get each model that you wish to see.
Dan Obermiller