diff --git a/packages/signal-polyfill/src/wrapper.spec.ts b/packages/signal-polyfill/src/wrapper.spec.ts
index 1b50ef8..be08e95 100644
--- a/packages/signal-polyfill/src/wrapper.spec.ts
+++ b/packages/signal-polyfill/src/wrapper.spec.ts
@@ -225,6 +225,20 @@ describe("Watcher", () => {
     signal.set(1);
     expect(mockGetPending).toBeCalled();
   });
+
+  it("does not store duplicated watchers for the same signal", () => {
+    const watcher = new Signal.subtle.Watcher(() => {});
+    const signal = new Signal.State<number>(0);
+    const computed = new Signal.Computed(() => signal.get() + 1);
+    watcher.watch(signal);
+    watcher.watch(signal);
+    watcher.watch(computed);
+    watcher.watch(computed);
+    watcher.watch(computed);
+    expect(Signal.subtle.introspectSources(watcher).length).toBe(2);
+    expect(Signal.subtle.introspectSources(watcher)[0]).toBe(signal);
+    expect(Signal.subtle.introspectSources(watcher)[1]).toBe(computed);
+  });
 });
 
 describe("Expected class shape", () => {
diff --git a/packages/signal-polyfill/src/wrapper.ts b/packages/signal-polyfill/src/wrapper.ts
index a8eab3d..99cdb28 100644
--- a/packages/signal-polyfill/src/wrapper.ts
+++ b/packages/signal-polyfill/src/wrapper.ts
@@ -234,10 +234,15 @@ export namespace subtle {
       this.#assertSignals(signals);
 
       const node = this[NODE];
+      assertConsumerNode(node);
+
       node.dirty = false;  // Give the watcher a chance to trigger again
       const prev = setActiveConsumer(node);
+
       for (const signal of signals) {
-        producerAccessed(signal[NODE]);
+        if(!node.producerNode.includes(signal[NODE])) {
+          producerAccessed(signal[NODE]);
+        }
       }
       setActiveConsumer(prev);
     }