No, it is not. The word "topping" is the present participle of the verb to top, and may be a verb or a noun (gerund).
Daniel Topping's birth name is Daniel Reid Topping.
Lynne Topping's birth name is Lynne Edea Topping.
James Topping was born on 1974-12-18.
Charles E. Topping has written: 'Topping genealogy (also Tapping)'
No, then is not a preposition. It is a conjuction.Than is a preposition.
Harry Topping died in 2001.
Seymour Topping was born in 1921.
Michael Topping died in 1796.
Michael Topping was born in 1747.
Norman Topping died in 1997.
Norman Topping was born in 1908.
Walter Topping was born in 1908.