Duplicated config dependencies in base field overrides configuration files

Sometimes, when doing a "drush cex" configuration export, some configs are added each time the command is executed. For example:

- File core.base_field_override.node.article.CUSTOM_OPTION.yml:

langcode: en
status: true
dependencies:
  config:
    - node.type.article
    - custom_pub.custom_publishing_option.CUSTOM_OPTION
    - custom_pub.custom_publishing_option.CUSTOM_OPTION
    - custom_pub.custom_publishing_option.CUSTOM_OPTION
   # And more and more "custom_pub.custom_publishing_option.CUSTOM_OPTION" each time configuration is exported.
id: node.article.CUSTOM_OPTION
field_name: CUSTOM_OPTION
entity_type: node
bundle: article
label: 'My custom option'
description: 'This is a custom option'
required: false
translatable: true
default_value:
  -
    value: 0
default_value_callback: ''
settings:
  on_label: 'On'
  off_label: 'Off'
field_type: boolean

I've noticed this is caused due to a missing validation at custom_pub_entity_presave module function.

Patch on the way.