The timpani has different names in different countries
The word "timpani" is the plural form of timpano in Italian. As the timpani has been set up in a pair of two or more since long ago, the plural form, timpani is always used. In German-speaking regions as well, the timpani is called a pauken, which is the plural form.
In the U.S.A., the word is occasionally found misspelled as "timpany", and the instrument is also called the kettledrum.
The kettle is also named differently in different countries. In Germany, it is called a kessel, and in the U.S. it is called a kettle or a bowl. The word "kettle" means different things in different places. "Kettle" in English refers to a round pot with a deep base in the U.S., but often means a stove pot in the U.K. This may be why there are so many names used now.