Short answer: Yes.
DW Support responded thusly:
After some testing and confirmation on our end, there are two ways we could find.
Set auto index job to use file cabinet for processing list.
Set auto index job to use "Use all data records for indexing" with the multiple matches option.
Create .csv that would have multiple lines with the same match code. the multiple lines would just need the match code and the value for the keyword filled out.
This would require good filters on the cabinet side of the AIX job if it is a large cabinet as well. See below for example of csv setup.
2,Customer 2, 11111
This is very easy to set up too.
Created a text file with multiple sections for the same keyword field. In this case Invoice#,Invoice#2,Invoice#3,etc.
Then I created one AI job that populates all fields. This AI job points to the first Invoice# section in the text file.
Then I copied that job and modified it to not populate any fields except for the Invoice# using the second Invoice#2 section of the text file.
Then I repeated this for the third Invoice#3 section. And so on.
Run all three jobs and you should get the results I wanted.