It would be "cleaner" if you use symbolic links (no two copies of the file). Or does amazon's OS doesn't read links?
Code:
ln -s "$KEY_DIR/pubprodkey01.pem.$ACTIVE" "$KEY_DIR/pubprodkey01.pem"
ln -s "$KEY_DIR/pubprodkey02.pem.$ACTIVE" "$KEY_DIR/pubprodkey02.pem"