Parts 'checkbox-support-dev' and 'plainbox-dev' have the following file paths in common which have different contents:
    lib/python3.5/site-packages/pip-9.0.1.dist-info/RECORD
    lib/python3.5/site-packages/setuptools-34.1.1.dist-info/RECORD
    lib/python3.5/site-packages/wheel-0.29.0.dist-info/RECORD

Snapcraft offers some capabilities to solve this by use of the following keywords:
    - `filesets`
    - `stage`
    - `snap`
    - `organize`

Learn more about these part keywords by running `snapcraft help plugins`