Can I MERGE TWO RECORDS?
If I'm right, your issue is that you have a field in a section that has duplicated options. You want to remove one of the options but also change the records that selected this option to be the correct one? If that's the case, you can do the following steps:
1. Find the duplicated option value (depending on how you set up the dropdown). Say the field has 'option one' and 'duplicated option one', you just take notes of duplicated option one value
2. Remove the duplicated option (duplicated option one)
3. In the url, add a search statement to find the records with the option. For example:
Original url: yourdomain.com/cmsb/admin.php?menu=section_name
If the field name is "test_field"
Search url: yourdomain.com/cmsb/admin.php?menu=section_name&test_field=duplicated_option_one_value
4. Modify the search result. Change the records to correct option
Let me know if you have any questions!