Jambalaya is the hallmark Creole dish but it varies widely from cook to cook. It can be cooked with almost any kind of meat, poultry, or shellfish. So yes, this basic recipe could certainly be altered to include additional meats or substitutions. To keep it basic, I think one is enough. It's the right balance of veggies, starch and protein. Another meat would throw that off, unless you were making a larger portion. Plus, it becomes less simple! I love the cajun flavor of the Andouille, but I have also used Kielbasa, a similar Polish smoked sausage. Both work fine, Andouille can be on the spicier side, so check what the package says.