While this topic can be of some debate among professionals, here is a break down the terms, what they mean and how they relate to one another.
The designer however is not always the person writing the code and can even work totally independent of the ones writing the code or will ultimately be responsible for the website. The designer’s job is creative process that uses their imagination and intuition to bring together various parts of a website into a collective whole. Designers can come from practically any background but are commonly associated with graphic design and art in general. A designer will usually showcase their skills with a portfolio containing past works from previous employers to help persuade future prospects of their skills and capabilities.
Can these two roles really be filled by one person?
So in short to answer the question, yes I'd say MWDS is proof that someone can be both a designer and a developer. Don't just take my word for it, see what some of my customers have said about it.