ERROR: Duplicate mount points

version: '2'
services:

  python:
    build: docker/python
    container_name: ${PYTHON_CONTAINER}

    volumes:
      - ./app:/var/www/html
      - ./common/python:/var/www/html/common

    working_dir: /var/www/html

    networks:
      - some-back

    depends_on:
      - db

    environment:
      SERVICE_NAME: ${CONTAINER}

      POSTGRES_HOST: ${POSTGRES_HOST}
      POSTGRES_PORT: ${POSTGRES_PORT}
      POSTGRES_DB: ${POSTGRES_DB}
      POSTGRES_USER: ${POSTGRES_USER}
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}

  db:
    build: docker/postgis
    container_name: ${DB_CONTAINER}

    volumes:
      - ${POSTGRES_DATA}:/${POSTGRES_DATA}

    networks:
      - some-back

    environment:
      POSTGRES_USER: ${POSTGRES_USER}
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
      POSTGRES_DB: ${POSTGRES_DB}
      PGDATA: /${POSTGRES_DATA}
      VER_POSTGRES: ${VER_POSTGRES}
 
networks:
  some-back:
    external: true

version: '2'
services:

  python:
    tty: true

    ports:
      - "${WEB_PORT_EXT}:${WEB_PORT_INT}"

    environment:
      ENV: dev
      CONTAINER: ${CONTAINER}

ERROR: Duplicate mount points: [/home/user/auth/dbdata:/dbdata:rw, /home/user/auth/dbdata:/dbdata:rw]