from configparser import ConfigParser

config = ConfigParser(allow_unnamed_section=True)
config.read(['first.ini', 'second.ini'])

# now the unnamed section contains values ​​only from the second file:
print(config._sections)
# {
# <UNNAMED_SECTION>: {'second_unnamed_option1': '1', 'second_unnamed_option2': '2'},
# 'first_section': {'first_section_option1': '1', 'first_section_option2': '2'},
# 'second_section': {'second_section_option1': '1', 'second_section_option2': '2'}
# }