Answer:
Yes they are.
A element is characterized by the number of protons it has. As the number of protons is the same, then deuterium and protium are the same element, Hydrogen.
Explanation:
What you are seeing is the phenomenon of Isotopy. That happens, isotopy, every time that one atom has the same quantity of protons of another, but a different mass. That difference is caused by the number of neutrons, which variates.
