diff --git a/src/libos/src/fs/file_ops/dup.rs b/src/libos/src/fs/file_ops/dup.rs
index 52bd9847..fc07a9eb 100644
--- a/src/libos/src/fs/file_ops/dup.rs
+++ b/src/libos/src/fs/file_ops/dup.rs
@@ -23,7 +23,10 @@ pub fn do_dup2(old_fd: FileDesc, new_fd: FileDesc) -> Result<FileDesc> {
     }
 
     if old_fd != new_fd {
-        files.put_at(new_fd, file, false);
+        if let Some(old_file) = files.put_at(new_fd, file, false) {
+            // If the file descriptor `new_fd` was previously open, close it silently.
+            old_file.release_advisory_locks()
+        }
     }
     Ok(new_fd)
 }
@@ -46,6 +49,9 @@ pub fn do_dup3(old_fd: FileDesc, new_fd: FileDesc, flags: u32) -> Result<FileDes
     if old_fd == new_fd {
         return_errno!(EINVAL, "old_fd must not be equal to new_fd");
     }
-    files.put_at(new_fd, file, creation_flags.must_close_on_spawn());
+    if let Some(old_file) = files.put_at(new_fd, file, creation_flags.must_close_on_spawn()) {
+        // If the file descriptor `new_fd` was previously open, close it silently.
+        old_file.release_advisory_locks()
+    }
     Ok(new_fd)
 }
diff --git a/src/libos/src/fs/file_table.rs b/src/libos/src/fs/file_table.rs
index 5d5a1fca..738b7d23 100644
--- a/src/libos/src/fs/file_table.rs
+++ b/src/libos/src/fs/file_table.rs
@@ -86,7 +86,7 @@ impl FileTable {
         min_free_fd as FileDesc
     }
 
-    pub fn put_at(&mut self, fd: FileDesc, file: FileRef, close_on_spawn: bool) {
+    pub fn put_at(&mut self, fd: FileDesc, file: FileRef, close_on_spawn: bool) -> Option<FileRef> {
         let mut table = &mut self.table;
         let mut table_entry = Some(FileTableEntry::new(file, close_on_spawn));
         if fd as usize >= table.len() {
@@ -96,6 +96,7 @@ impl FileTable {
         if table_entry.is_none() {
             self.num_fds += 1;
         }
+        table_entry.map(|entry| entry.file.clone())
     }
 
     pub fn fds(&self) -> Vec<FileDesc> {