Merge several Excel files into one sheet with Duaer

Merge Excel files in Duaer

1. Add Form Trigger with one File field labelled Sheets, Multiple Files on, Accepted File Types .xlsx,.xls.
2. Add Code, rename it Split files, and paste the code below for one item per file.
3. Add Extract from File with Operation Extract From XLSX. Keep the defaults when headers are in row one; set Sheet Name under Options to read one sheet. Each row becomes an item.
4. Add Edit Fields, turn on Include Other Input Fields, and add source with {{ $('Split files').item.json.fileName }}.
5. To drop duplicates, add Remove Duplicates and compare on a key column such as order number.
6. Add Convert to File with Operation Convert to XLSX for one combined sheet.

const out = [];
for (const item of $input.all()) {
  for (const key of Object.keys(item.binary ?? {})) {
    out.push({
      json: { ...item.json, fileName: item.binary[key].fileName },
      binary: { data: item.binary[key] },
    });
  }
}
return out;

When column names differ

Duaer merges by column name. The same column named Amount in one file and Total in another becomes two columns. Rename them to one name in Edit Fields before exporting.