diff --git a/internal/process/inbox.go b/internal/process/inbox.go
index e26b1f7..f3eb36b 100644
--- a/internal/process/inbox.go
+++ b/internal/process/inbox.go
@@ -44,6 +44,22 @@ func (inbox *Inbox) Process() (*InboxResult, error) {
 		return &InboxResult{}, fmt.Errorf("%w: %v", ErrInboxProcess, err)
 	}
 
+	// deduplicate
+	taskKeys := map[string]*task.Task{}
+	for _, newT := range tasks {
+		existingT, ok := taskKeys[newT.Id]
+		switch {
+		case !ok:
+			taskKeys[newT.Id] = newT
+		case newT.Version >= existingT.Version:
+			taskKeys[newT.Id] = newT
+		}
+	}
+	tasks = []*task.Task{}
+	for _, t := range taskKeys {
+		tasks = append(tasks, t)
+	}
+
 	// split them
 	doneTasks, updateTasks := []*task.Task{}, []*task.Task{}
 	for _, t := range tasks {
diff --git a/internal/process/inbox_test.go b/internal/process/inbox_test.go
index 54d8f1c..c425426 100644
--- a/internal/process/inbox_test.go
+++ b/internal/process/inbox_test.go
@@ -35,15 +35,15 @@ func TestInboxProcess(t *testing.T) {
 					},
 					{
 						Subject: "to recurring",
-						Body:    "recur: 2021-05-14, daily\nid: xxx-xxx\nversion: 1",
+						Body:    "recur: 2021-05-14, daily\nid: xxx-xxx-a\nversion: 1",
 					},
 					{
 						Subject: "to planned",
-						Body:    "due: 2021-05-14\nid: xxx-xxx\nversion: 1",
+						Body:    "due: 2021-05-14\nid: xxx-xxx-b\nversion: 1",
 					},
 					{
 						Subject: "to unplanned",
-						Body:    "id: xxx-xxx\nversion: 1",
+						Body:    "id: xxx-xxx-c\nversion: 1",
 					},
 				},
 			},
@@ -110,6 +110,30 @@ func TestInboxProcess(t *testing.T) {
 				task.FOLDER_UNPLANNED: {},
 			},
 		},
+		{
+			name: "deduplicate",
+			messages: map[string][]*mstore.Message{
+				task.FOLDER_INBOX: {
+					{
+						Subject: "version 2",
+						Body:    "id: xxx-xxx\nversion: 1\n",
+					},
+					{
+						Subject: "version 2b",
+						Body:    "id: xxx-xxx\nversion: 1\n",
+					},
+				},
+				task.FOLDER_UNPLANNED: {{
+					Subject: "the task",
+					Body:    "id: xxx-xxx\nversion: 1\n",
+				}},
+			},
+			expCount: 1,
+			expMsgs: map[string][]*mstore.Message{
+				task.FOLDER_INBOX:     {},
+				task.FOLDER_UNPLANNED: {{Subject: "version 2b"}},
+			},
+		},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			mstorer, err := mstore.NewMemory([]string{