Rahman is special name of Allah which can not be given to people.
هَلْ تَعْلَمُ لَهُ سَمِيًّا
Do you know any other of the same name as His?
~ Surah Maryam
Mushfiqur Rahman and Mahbubur Rahman are allowed names because they are like Abdur Rahman, For example Abdur Rahman means slave of Rahman, Mahbubur Rahman means beloved by Rahman, I think Mushfiqur ...