diff --git a/rslib/src/import_export/package/apkg/import.rs b/rslib/src/import_export/package/apkg/import.rs
index 7acee2cd7..1edd16168 100644
--- a/rslib/src/import_export/package/apkg/import.rs
+++ b/rslib/src/import_export/package/apkg/import.rs
@@ -434,7 +434,7 @@ impl<'a> Context<'a> {
         for mut entry in mem::take(&mut self.data.revlog) {
             if self.added_cards.contains(&entry.cid) {
                 entry.usn = self.usn;
-                self.target_col.add_revlog_entry_undoable(entry)?;
+                self.target_col.add_revlog_entry_if_unique_undoable(entry)?;
             }
         }
         Ok(())
diff --git a/rslib/src/revlog/undo.rs b/rslib/src/revlog/undo.rs
index 24ea6f61a..71602f0cc 100644
--- a/rslib/src/revlog/undo.rs
+++ b/rslib/src/revlog/undo.rs
@@ -28,9 +28,17 @@ impl Collection {
 
     /// Add the provided revlog entry, modifying the ID if it is not unique.
     pub(crate) fn add_revlog_entry_undoable(&mut self, mut entry: RevlogEntry) -> Result<RevlogId> {
-        entry.id = self.storage.add_revlog_entry(&entry, true)?;
+        entry.id = self.storage.add_revlog_entry(&entry, true)?.unwrap();
         let id = entry.id;
         self.save_undo(UndoableRevlogChange::Added(Box::new(entry)));
         Ok(id)
     }
+
+    /// Add the provided revlog entry, if its ID is unique.
+    pub(crate) fn add_revlog_entry_if_unique_undoable(&mut self, entry: RevlogEntry) -> Result<()> {
+        if self.storage.add_revlog_entry(&entry, false)?.is_some() {
+            self.save_undo(UndoableRevlogChange::Added(Box::new(entry)));
+        }
+        Ok(())
+    }
 }
diff --git a/rslib/src/storage/revlog/mod.rs b/rslib/src/storage/revlog/mod.rs
index 27ee78ed8..d18d321e4 100644
--- a/rslib/src/storage/revlog/mod.rs
+++ b/rslib/src/storage/revlog/mod.rs
@@ -61,16 +61,19 @@ impl SqliteStorage {
         Ok(())
     }
 
-    /// Returns the used id, which may differ if `ensure_unique` is true.
+    /// Adds the entry, if its id is unique. If it is not, and `uniquify` is true,
+    /// adds it with a new id. Returns the added id.
+    /// (I.e., the option is safe to unwrap, if `uniquify` is true.)
     pub(crate) fn add_revlog_entry(
         &self,
         entry: &RevlogEntry,
-        ensure_unique: bool,
-    ) -> Result<RevlogId> {
-        self.db
+        uniquify: bool,
+    ) -> Result<Option<RevlogId>> {
+        let added = self
+            .db
             .prepare_cached(include_str!("add.sql"))?
             .execute(params![
-                ensure_unique,
+                uniquify,
                 entry.id,
                 entry.cid,
                 entry.usn,
@@ -81,7 +84,7 @@ impl SqliteStorage {
                 entry.taken_millis,
                 entry.review_kind as u8
             ])?;
-        Ok(RevlogId(self.db.last_insert_rowid()))
+        Ok((added > 0).then(|| RevlogId(self.db.last_insert_rowid())))
     }
 
     pub(crate) fn get_revlog_entry(&self, id: RevlogId) -> Result<Option<RevlogEntry>> {