Yes. As someone who lives in Vietnam and has a colleague called Anh (in this case a she).
Ha is the surname, Anh the first name. generally in Vietnam if you are older than the individual, or friendly you would refer to him only by his first name, Anh. If you were younger or being formal you would refer to him by both the first and middle names, Anh The. or Mr Ha... It shows respect for the individual using the names in that way in Vietnam.
You can also use just the middle names, again this is more formal. I have a colleague Hoa Lan (means Orchid) and I call her Hoa Lan, as she is a senior individual in the office and older, but then we have another lady who is even more senior (in that she has been in the company longer), rather than being more senior..... and everyone just refers to her as Lan, her middle name.
Hierarchy is a big thing in Vietnam, and respect comes from age and time served...