There are several types of cress, but the recipe in question is actually calling for watercress in two forms - one finely chopped and the other uncut sprigs. Some recipe writers want to be very sure you don’t mistake their intentions, so they’ll put the same ingredient in the recipe multiple times if it is used in different parts of the recipe, at different times, or, as here, is prepped differently. This is especially true with some common ingredients like butter. You might butter the pan and stir some melted butter in the batter, so the writer might put butter on two different ingredient lines or say something like, "8 Tbsp + 2 Tbsp butter."
Now, getting back to cresses, a number of varieties grow in water, but the only cultivated one is the watercress. The next most popular cress is the mustardy garden cress. All the other varieties seem to have at least two names each. Wild cress, dittander, or poor man’s pepper is one, Virginia cress, pepperwort, or peppergrass is another, and both are peppery. Curly cress or peppercress, and broadleaf cress or cressida, are two other types that grow in the United States. There is also a Brazilian cress, called pará and an Australian cress, known as the toothache plant. All cresses are generally pungent in taste, but watercress is among the mildest.