Salivary amylase digest starch to maltose in the mouth while chewing takes place. Why is it beneficial to have the enzyme that digest starch, amylase, in two different locations

Chemical digestion initiates in mouth with salivary digestion of starch.

Saliva contains amylase enzyme, or Ptyalin.

Salivary Amylase act on raw form of carbohydrates

Pancreatic amylase is released by the pancreas into the duodenum.

Pancreatic amylase work on complex form of carbohydrates and carbohydrates entering the intestine after partial digestion that remains undigested by salivary amylase.

Thus, two amylases ensure that all carbohydrate forms are converted to simpler form or glucose.