diff --git a/src/uu/cp/src/cp.rs b/src/uu/cp/src/cp.rs
index 62509b7564..32168b0900 100644
--- a/src/uu/cp/src/cp.rs
+++ b/src/uu/cp/src/cp.rs
@@ -29,7 +29,7 @@ use platform::copy_on_write;
 use uucore::display::Quotable;
 use uucore::error::{set_exit_code, UClapError, UError, UResult, UUsageError};
 use uucore::fs::{
-    are_hardlinks_to_same_file, canonicalize, get_filename, is_symlink_loop,
+    are_hardlinks_to_same_file, canonicalize, get_filename, is_symlink_loop, normalize_path,
     path_ends_with_terminator, paths_refer_to_same_file, FileInformation, MissingHandling,
     ResolveMode,
 };
@@ -1264,9 +1264,17 @@ pub fn copy(sources: &[PathBuf], target: &Path, options: &Options) -> CopyResult
     };
 
     for source in sources {
-        if seen_sources.contains(source) {
-            // FIXME: compare sources by the actual file they point to, not their path. (e.g. dir/file == dir/../dir/file in most cases)
-            show_warning!("source file {} specified more than once", source.quote());
+        let normalized_source = normalize_path(source);
+        if options.backup == BackupMode::NoBackup && seen_sources.contains(&normalized_source) {
+            let file_type = if source.symlink_metadata()?.file_type().is_dir() {
+                "directory"
+            } else {
+                "file"
+            };
+            show_warning!(
+                "source {file_type} {} specified more than once",
+                source.quote()
+            );
         } else {
             let dest = construct_dest_path(source, target, target_type, options)
                 .unwrap_or_else(|_| target.to_path_buf());
@@ -1309,7 +1317,7 @@ pub fn copy(sources: &[PathBuf], target: &Path, options: &Options) -> CopyResult
                 copied_destinations.insert(dest.clone());
             }
         }
-        seen_sources.insert(source);
+        seen_sources.insert(normalized_source);
     }
 
     if let Some(pb) = progress_bar {
diff --git a/tests/by-util/test_cp.rs b/tests/by-util/test_cp.rs
index 0fba59672c..156daec1f1 100644
--- a/tests/by-util/test_cp.rs
+++ b/tests/by-util/test_cp.rs
@@ -121,6 +121,60 @@ fn test_cp_duplicate_files() {
     assert_eq!(at.read(TEST_COPY_TO_FOLDER_FILE), "Hello, World!\n");
 }
 
+#[test]
+fn test_cp_duplicate_folder() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    ucmd.arg("-r")
+        .arg(TEST_COPY_FROM_FOLDER)
+        .arg(TEST_COPY_FROM_FOLDER)
+        .arg(TEST_COPY_TO_FOLDER)
+        .succeeds()
+        .stderr_contains(format!(
+            "source directory '{TEST_COPY_FROM_FOLDER}' specified more than once"
+        ));
+    assert!(at.dir_exists(format!("{TEST_COPY_TO_FOLDER}/{TEST_COPY_FROM_FOLDER}").as_str()));
+}
+
+#[test]
+fn test_cp_duplicate_files_normalized_path() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg(format!("./{TEST_HELLO_WORLD_SOURCE}"))
+        .arg(TEST_COPY_TO_FOLDER)
+        .succeeds()
+        .stderr_contains(format!(
+            "source file './{TEST_HELLO_WORLD_SOURCE}' specified more than once"
+        ));
+    assert_eq!(at.read(TEST_COPY_TO_FOLDER_FILE), "Hello, World!\n");
+}
+
+#[test]
+fn test_cp_duplicate_files_with_plain_backup() {
+    let (_, mut ucmd) = at_and_ucmd!();
+    ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg(TEST_HELLO_WORLD_SOURCE)
+        .arg(TEST_COPY_TO_FOLDER)
+        .arg("--backup")
+        .fails()
+        // cp would skip duplicate src check and fail when it tries to overwrite the "just-created" file.
+        .stderr_contains(
+            "will not overwrite just-created 'hello_dir/hello_world.txt' with 'hello_world.txt",
+        );
+}
+
+#[test]
+fn test_cp_duplicate_files_with_numbered_backup() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    // cp would skip duplicate src check and succeeds
+    ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg(TEST_HELLO_WORLD_SOURCE)
+        .arg(TEST_COPY_TO_FOLDER)
+        .arg("--backup=numbered")
+        .succeeds();
+    at.file_exists(TEST_COPY_TO_FOLDER_FILE);
+    at.file_exists(format!("{TEST_COPY_TO_FOLDER}.~1~"));
+}
+
 #[test]
 fn test_cp_same_file() {
     let (at, mut ucmd) = at_and_ucmd!();