We are currently tracking an issue where if you use the following in your list assignment there are 2 leads created in your lead object.
-- ALL CAPTURES » List: Add lead De-Duplication: None - Create New Record
The following will remove any chance that iCapture is causing the duplication on our integration.
Step 1 - Create a new text field in Salesforce with the following parameters.
Name and label can be up to your choosing
Unique: Do not allow duplicate Values - Treat "ABC" and "abc" as duplicate values (case insensitive)
Step 2 - Add the merge field in your data mapping to the new field
You will see a red error at the top of the page stating that the mapping contains and invalid merge field. Ignore the error and save the mapping.
Since the capid is a unique number to each capture, this will let the first lead be created, but should return an error if it tries to get duplicated.
If you are still getting duplicate entries we recommend you contact Salesforce to see if they can determine what is causing the duplication.