How MySql Join two tables with Checkboxes results stored as "string" data format?
You need to group by the submission_id:
like:
SELECT submission_id sub_id,
GROUP_CONCAT(DISTINCT c1.option_name)datimkt
FROM form_results d
JOIN field_options c1 ON FIND_IN_SET(c1.option_value, d.datimkt)
GROUP BY sub_id;