Can you add an invisible DupeFlag element to the form, then maybe one of these?

1. Can you run Remove Duplicate Records to ID the result set, then run the report or do a mass update to a DupeFlag on each record in the result set?

OR

2. On all records, vs. Remove Duplicates, write out the record to a string, loop through records also writing to strings.  Compare strings and value to DupeFlag element if strings match?  Now all duplicates will have a value set in the DupeFlag field. 

But will consume time because will have to write out record1, compare all others to it, setting flags.  Then write out record2 and compare all others to that one, setting flags.  Repeating for every record.  Can be reduced by retreiving only those records that are likely to be dupes, ie: only records that have same PO number.