diff --git a/crates/ui-egui/src/combine_ui.rs b/crates/ui-egui/src/combine_ui.rs
index 22aa16ff..467a040b 100644
--- a/crates/ui-egui/src/combine_ui.rs
+++ b/crates/ui-egui/src/combine_ui.rs
@@ -402,6 +402,9 @@ pub struct CombineFile {
     pub(crate) group: u64,
     pub name: String,
     pub bytes: Arc<Vec<u8>>,
+    /// The file as it was added: `bytes` itself for a PDF, the image or text it was made from
+    /// otherwise (converted anew, with its own date, each time it is added).
+    source: Arc<Vec<u8>>,
     pub pages: usize,
     /// Each page's displayed size in points; shared, so undo snapshots don't copy it.
     pub(crate) sizes: Arc<[(f32, f32)]>,
@@ -440,7 +443,7 @@ impl CombineTab {
         // unrelated files, and never count a source split into parts as several additions.
         let mut candidates: HashMap<(&str, usize), Vec<usize>> = HashMap::new();
         for (i, f) in files.iter().enumerate() {
-            candidates.entry((&f.name, f.bytes.len())).or_default().push(i);
+            candidates.entry((&f.name, f.source.len())).or_default().push(i);
         }
         let mut twice = vec![false; files.len()];
         for indices in candidates.values() {
@@ -452,7 +455,7 @@ impl CombineTab {
             let mut contents: HashMap<&[u8], Vec<usize>> = HashMap::new();
             for &i in indices {
                 if let Some(f) = files.get(i) {
-                    contents.entry(f.bytes.as_slice()).or_default().push(i);
+                    contents.entry(f.source.as_slice()).or_default().push(i);
                 }
             }
             for copies in contents.values() {
@@ -2405,6 +2408,7 @@ impl PdfCraftApp {
                 lock: None,
                 notes: Vec::new(),
             };
+            let source = bytes.clone();
             let (bytes, assessed) = match self.session.as_pdf(&name, &bytes) {
                 Ok(pdf) => {
                     let assessed = assess(&pdf, None);
@@ -2433,6 +2437,7 @@ impl PdfCraftApp {
                 group: 0,
                 name,
                 bytes,
+                source,
                 pages: 0,
                 range: String::new(),
                 modified,
@@ -2646,6 +2651,28 @@ mod tests {
         assert!(app.combine_tab.duplicate_warnings(&app.combine_draft).is_empty());
     }
 
+    /// #1303: an image or text file is converted anew, with its own date, each time it is added,
+    /// so it is the file as added that is compared, not the PDF made from it.
+    #[test]
+    fn the_same_image_or_text_file_added_twice_is_a_duplicate() {
+        static NOW: std::sync::atomic::AtomicI64 = std::sync::atomic::AtomicI64::new(1_700_000_000);
+        let mut png = std::io::Cursor::new(Vec::new());
+        image::RgbaImage::from_pixel(12, 4, image::Rgba([20, 30, 40, 255])).write_to(&mut png, image::ImageFormat::Png).unwrap();
+        let png = png.into_inner();
+        let warnings = |first: (&str, &[u8]), second: (&str, &[u8])| {
+            let mut app = PdfCraftApp::new();
+            app.session = std::mem::take(&mut app.session).with_clock(|| NOW.fetch_add(1, std::sync::atomic::Ordering::Relaxed));
+            for (name, bytes) in [first, second] {
+                app.stage_combine(vec![(name.into(), bytes.to_vec())]);
+            }
+            assert_ne!(app.combine_draft[0].bytes, app.combine_draft[1].bytes, "each addition is converted with its own date");
+            app.combine_tab.duplicate_warnings(&app.combine_draft).to_vec()
+        };
+        assert_eq!(warnings(("notes.txt", b"Hello"), ("notes.txt", b"Hello")), [true, true], "the same text file");
+        assert_eq!(warnings(("photo.png", &png), ("photo.png", &png)), [true, true], "the same image");
+        assert_eq!(warnings(("notes.txt", b"Hello"), ("notes.txt", b"World")), [false, false], "different text, same name and size");
+    }
+
     #[test]
     fn every_read_of_a_file_is_new_even_after_undo() {
         // Regression: the read counter lived in the undo history, so unlock → undo → unlock (with