fix(QFile): (backport from Qv2) files wrongly marked as duplicated wh…

…en non-append after subsequent file picking #14406

ui/src/mixins/file.js

@@ -124,11 +124,13 @@ export default {
         file.__key = file.webkitRelativePath + file.lastModified + file.name + file.size
       })
 
-      // Avoid duplicate files
-      const filenameMap = currentFileList.map(entry => entry.__key)
-      files = filterFiles(files, rejectedFiles, 'duplicate', file => {
-        return filenameMap.includes(file.__key) === false
-      })
+      if (append !== true) {
+        // Avoid duplicate files
+        const filenameMap = currentFileList.map(entry => entry.__key)
+        files = filterFiles(files, rejectedFiles, 'duplicate', file => {
+          return filenameMap.includes(file.__key) === false
+        })
+      }
 
       if (files.length === 0) { return done() }