diff --git a/pttodoer/src/main.rs b/pttodoer/src/main.rs
index 986e755..e10b6a6 100644
--- a/pttodoer/src/main.rs
+++ b/pttodoer/src/main.rs
@@ -161,7 +161,7 @@ impl DB {
          for task in &edited.tasks.0 {
             if task.is_due() {
                now_due.push(task.clone());
-            } else {
+            } else if !not_due.tasks.0.contains(task) {
                not_due.tasks.0.push(task.clone());
             }
          }