diff --git a/.changeset/short-lions-search.md b/.changeset/short-lions-search.md
new file mode 100644
index 0000000000..ed3abdc053
--- /dev/null
+++ b/.changeset/short-lions-search.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: only output the key for each_key_duplicate
diff --git a/packages/svelte/src/internal/client/validate.js b/packages/svelte/src/internal/client/validate.js
index c3b1821947..eddcb69d9e 100644
--- a/packages/svelte/src/internal/client/validate.js
+++ b/packages/svelte/src/internal/client/validate.js
@@ -37,7 +37,7 @@ export function validate_each_keys(collection, key_fn) {
 				const b = String(i);
 
 				/** @type {string | null} */
-				let k = String(array[i]);
+				let k = String(key);
 				if (k.startsWith('[object ')) k = null;
 
 				e.each_key_duplicate(a, b, k);