The file upload field returns an object from getFieldValues. The object contains a list of all of the files that were uploaded or an empty array if a file was removed from the field.

I threw together a quick example of how this would work for both having a duplicate check within each row of the table and a multiline field outside of the table. I commented all of the lines of code so you know what is going on. NOTE: this code does not handle a user removing a row from the table, but it does handle a user removing a file from the upload field.

I encourage you to review the code and make sure you understand what it is doing before implementing it in any production code, but I am happy to explain anything you need!

const formFields = {
  multiline: { fieldId: 70 },
  uploadColumn: { fieldId: 69 },
  isDuplicateColumn: { fieldId: 46 },
}

LFForm.onFieldChange(async (ev) => {
  // get fieldId and row number from the event that fired
  const { fieldId, index } = ev.options[0];
  if (fieldId === undefined) return;
  // create a formFieldId object to get the value of the field
  const formFieldId = { fieldId };
  // When field is in a table/collection index = row number, so lets only focus on that row
  if (index !== undefined && index !== -1) formFieldId.index = index;
  // get the value of the field that changed
  /**
   * @type {Array<{ name: string, size: string }>}
   */
  const changedValue = LFForm.getFieldValues(formFieldId);
  console.log('Field changed:', formFieldId, changedValue);

  /**
   * @type {{ name: string, size: string }[][]}
   */
  const allUploadFieldValues = LFForm.getFieldValues(formFields.uploadColumn);

  // reset current field duplicate status
  await LFForm.setFieldValues(formFields.isDuplicateColumn, '', { index });
  const allFileNames = new Set();
  const dupes = new Set();
  for (let i = 0; i < allUploadFieldValues.length; i++) {
    const fieldValue = allUploadFieldValues[i];
    if (index !== undefined && index !== -1 && i === index) continue; // skip current row
    // Only one file allowed per upload field so grab first from the array
    const file = fieldValue[0];
    if (!file) continue; // skip empty rows
    // create a unique key for each file based on name and size
    const fileKey = `${file.name}-${file.size}`;
    // check if the file key already exists in the set
    if (allFileNames.has(fileKey)) {
      dupes.add(file.name);
    } else {
      allFileNames.add(fileKey);
    }

    const isDuplicate = changedValue[0] && file.name === changedValue[0].name && file.size === changedValue[0].size;
    if (isDuplicate) {
      dupes.add(file.name);
      const isDuplicateColumnFieldId = formFields.isDuplicateColumn.fieldId;
      try {

        // set the duplicate status for the current row
        await LFForm.setFieldValues(formFields.isDuplicateColumn, 'duplicate', { fieldId: isDuplicateColumnFieldId, index: i });
        // if the current row is a duplicate, set the duplicate status for the other rows that have the same file
        await LFForm.setFieldValues(formFields.isDuplicateColumn, 'duplicate', { fieldId: isDuplicateColumnFieldId, index });
      } catch (error) {
        // Remove this code if you don't have per row checking
      }
    }
  }
  const finalDupes = Array.from(dupes);
  console.log('mf dupes', finalDupes);
  await LFForm.setFieldValues(formFields.multiline, finalDupes.join(', '));

  // get list
}, formFields.uploadColumn);