diff --git a/crates/engine/src/cmd/data.rs b/crates/engine/src/cmd/data.rs
index 94733071c..7372380a4 100644
--- a/crates/engine/src/cmd/data.rs
+++ b/crates/engine/src/cmd/data.rs
@@ -691,8 +691,11 @@ fn remove_duplicates(s: &mut Session, p: &Json) -> Result<Json> {
         let Some(sh) = cx.wb.sheet(sheet) else { return Ok(()) };
         let mut seen = std::collections::HashSet::new();
         let mut keep: Vec<u32> = Vec::new();
+        // Cells are compared by the text they show, as in Excel: the same date in two formats
+        // isn't a duplicate, while 1.01 and 1.02 shown as 1.0 are.
+        let shown = |c: CellRef| crate::display::format(&sh.value(c), cx.wb.styles.get(sh.style_id(c)).num_fmt.as_str(), &cx.wb).text;
         for row in start..=r.end.row {
-            let key: Vec<String> = cols.iter().map(|c| sh.value(CellRef::new(row, *c)).display().to_lowercase()).collect();
+            let key: Vec<String> = cols.iter().map(|c| shown(CellRef::new(row, *c)).to_lowercase()).collect();
             if seen.insert(key) {
                 keep.push(row);
             } else {
diff --git a/crates/engine/src/tests.rs b/crates/engine/src/tests.rs
index 92ca38665..139a24985 100644
--- a/crates/engine/src/tests.rs
+++ b/crates/engine/src/tests.rs
@@ -615,6 +615,18 @@ fn case_sensitive_sort_puts_lowercase_first() {
     assert_eq!(col, ["a", "A", "aB", "Ab", "b", "B"].map(Value::from));
 }
 
+#[test]
+fn remove_duplicates_compares_shown_text() {
+    let mut s = s();
+    s.execute("range.setValues", json!({"range": "A1", "values": [["Date", "Price"], ["2006-03-08", 1.01], ["2006-03-08", 1.02]]})).unwrap();
+    s.execute("home.numberFormat", json!({"range": "A3", "code": "mmm d, yyyy"})).unwrap();
+    s.execute("home.numberFormat", json!({"range": "B2:B3", "code": "0.0"})).unwrap();
+    let r = s.execute("data.removeDuplicates", json!({"range": "A1:A3", "header": true})).unwrap();
+    assert_eq!(r["removed"], 0);
+    let r = s.execute("data.removeDuplicates", json!({"range": "B1:B3", "header": true})).unwrap();
+    assert_eq!(r["removed"], 1);
+}
+
 #[test]
 fn formatting_and_styles() {
     let mut s = s();