No; it's a list of the values of a field from the records in a found set – if that found set has duplicate values in that field, so does the list.
Are you just asking to confirm your suspicion, or do you want a method to de-duplicate that list? I think briandunning.com has a number of Custom Functions for that purpose (though some of them are truly terrible … ).
Writing your own recursive de-duplicator isn't that hard, and a nice exercise, if you're so inclined …
I wanted to understand how the Summary List function worked.
Thanks for the reply.
Sent from my iPad