How to go through the loop so that there are no duplicate elements?

Question

PHP

Hello, I'm scratching my head, I can not solve the problem. Help me please.
There is an array with available countries:

array(
  (int) 0 => array(
    'countries_users' => array(
      'id' => '1',
      'country_id' => '244',
      'user_id' => '6'
    )
  ),
  (int) 1 => array(
    'countries_users' => array(
      'id' => '2',
      'country_id' => '132',
      'user_id' => '6'
    )
  )
)

There are also other countries

spoiler

array(
  (int) 0 => array(
    'Country' => array(
      'id' => '132',
      'country_code' => 'MW',
      'country_name' => 'Malawi',
      'show_in_documents' => true
    )
  ),
  (int) 1 => array(
    'Country' => array(
      'id' => '152',
      'country_code' => 'NA',
      'country_name' => 'Namibia',
      'show_in_documents' => true
    )
  ),
  (int) 2 => array(
    'Country' => array(
      'id' => '200',
      'country_code' => 'ZA',
      'country_name' => 'South Africa',
      'show_in_documents' => true
    )
  ),
  (int) 3 => array(
    'Country' => array(
      'id' => '215',
      'country_code' => 'TZ',
      'country_name' => 'Tanzania, United Republic of',
      'show_in_documents' => true
    )
  ),
  (int) 4 => array(
    'Country' => array(
      'id' => '244',
      'country_code' => 'ZM',
      'country_name' => 'Zambia',
      'show_in_documents' => true
    )
  )
)

I can't bring them in and if<input type="checkbox">

countries_users['country_id'] == country['id']

are equal, then put checked. When I try, the countries start to duplicate.
Thanks for your help!