diff --git a/src/libs/cplusplus/CppDocument.cpp b/src/libs/cplusplus/CppDocument.cpp
index d28fdd50baa..07714c0fe2f 100644
--- a/src/libs/cplusplus/CppDocument.cpp
+++ b/src/libs/cplusplus/CppDocument.cpp
@@ -296,12 +296,13 @@ void Document::setLastModified(const QDateTime &lastModified)
     _lastModified = lastModified;
 }
 
-FilePaths Document::includedFiles() const
+FilePaths Document::includedFiles(Duplicates duplicates) const
 {
     FilePaths files;
     for (const Include &i : std::as_const(_resolvedIncludes))
         files.append(i.resolvedFileName());
-    FilePath::removeDuplicates(files);
+    if (duplicates == Duplicates::Remove)
+        FilePath::removeDuplicates(files);
     return files;
 }
 
@@ -771,7 +772,7 @@ QSet<FilePath> Snapshot::allIncludesForDocument(const FilePath &filePath) const
     while (!files.isEmpty()) {
         FilePath file = files.pop();
         if (Document::Ptr doc = document(file)) {
-            const FilePaths includedFiles = doc->includedFiles();
+            const FilePaths includedFiles = doc->includedFiles(Document::Duplicates::Keep);
             for (const FilePath &inc : includedFiles) {
                 if (!result.contains(inc)) {
                     result.insert(inc);
diff --git a/src/libs/cplusplus/CppDocument.h b/src/libs/cplusplus/CppDocument.h
index 679663f2d99..00bebf277d9 100644
--- a/src/libs/cplusplus/CppDocument.h
+++ b/src/libs/cplusplus/CppDocument.h
@@ -297,7 +297,12 @@ public:
         }
     };
 
-    Utils::FilePaths includedFiles() const;
+    enum class Duplicates {
+        Remove,
+        Keep,
+    };
+
+    Utils::FilePaths includedFiles(Duplicates duplicates = Duplicates::Remove) const;
     void addIncludeFile(const Include &include);
 
     const QList<Include> &resolvedIncludes() const