i don’t have any answers, Kev seems to’ve covered almost everything.  i only wonder, in this case of duplicate list entries, if the Apiname on the list entries is different than the values.

You asked a simple question that requires a fairly complex answer, because one must account for static and dynamic lists, as well as flat and cascading lists. 
The code below is a functioning groovy example of collecting list values for a given subclass and cell.
It works. i’m sure it can be improved, (i’m interested in any improvements to it).  it runs on Agile 9.3.6

// given:
// sdk – the agile session
// subclassName – the agile subclass name
// apiName – a given cell apiname
// return:
// the list of values, if any.

subclass = sdk.getAgileClass(subclassName)
attribute = subclass.getAttribute(apiName)
listName = attribute?.getProperty(‘List’)?.getValue()
list = sdk.getAdmin().getListLibrary().getAdminList(listName as String)

println “subclass|$subclass|attribute|$attribute|list|$list”

items = []

// STATIC LISTS
if( list.isEnumeratable() ) {

        // STATIC NON-CASCADED LISTS
        if( !list.isCascaded()) {
                items = list.getAdminList()?.getItems().findAll{it.isObsolete() == false} as String[]
        }
        // STATIC CASCADED LISTS
        else {
                items = []
                adminList = list.getAdminList()
                adminList.getItems().findAll{ it.isObsolete() == false}.each {
                        if (it.parentItemID == 0) {
                                it.children.each { items.add( “${it.name}|$it” )}
                        }
                }
        }

} else { // DYNAMIC LISTS — Use the list’s query to get its items.

        adminList = list.getAdminList()
        criteria = sdk.getAdmin().getNode( adminList.getCriteria().getProperties()[‘ID’] )
        QCLASS = (criteria) ? criteria.getCriteriaClass() : list.getListAgileClass()
        QQUERY = (criteria) ? criteria.getCriteria() : “”

        items = sdk.query( QCLASS, QQUERY ).collect { row ->

                value = row.getCells()[0]
                // you could handle special cases here, for example: 
                if( QCLASS.toString() == ‘Users’) {
                        fname = row.getValue(‘firstName’)
                        lname = row.getValue(‘lastName’)
                        uid = row.getValue(‘userID’)
                        value = “$fname $lname ($uid)”
                }
                return value
        }
// done.
}
println “items:(if any)”
items.each {println it}

Oracle provides a high-speed dataloader to select third-party support organizations, without support.
It’s been years since i used it, but we were able to load thousands of records in minutes. 
The Oracle Agile Support manager owns it & might provide the loader on request.