I have a repeating group that has, say, one record with a field (vendor) that is a list field with x list items.
What I am doing is copying that record x-1 times - I have managed this through a recursive workflow.
What I am struggling with is that I want to amend the vendor list in each of the records to end up with all vendors on a separate line - that is for example
Initial record has three vendors
Copy initial record twice, leaving three identical records
Remove all but vendor one from the first record, all but vendor two from the second record and so on
Since you are doing it using a recursive workflow, you might have a iteration parameter (assumption). select vendor item #parameter for each iteration
Run the workflow on a list of vendors. the parameters have vendor(single record) and the record (X as you mentioned). In the actions, Copy the record and create the Single Vendor from parameter.
Both the above would work. I personally would go for Second option.
Hope it works!