Excel udf called too many times

I have an excel function defined in a module, which is called the total twice as a sheet functional. However, when I make a shift + f9 and put a breakpoint on the function, I noticed that its call calls more than two times, about 5 times. However, this function is not called anywhere, either programmatically, or on any worksheet, except for the two cells mentioned above.

Also, when I look at the call stack when execution executes my function, it shows that my function is a top-level call. Any help regarding what could be causing this? Thank.