diff --git a/src/mock-doc/serialize-node.ts b/src/mock-doc/serialize-node.ts
index 23540a6a316..c94707d5743 100644
--- a/src/mock-doc/serialize-node.ts
+++ b/src/mock-doc/serialize-node.ts
@@ -1,4 +1,11 @@
-import { CONTENT_REF_ID, ORG_LOCATION_ID, SLOT_NODE_ID, TEXT_NODE_ID, XLINK_NS } from '../runtime/runtime-constants';
+import {
+  CONTENT_REF_ID,
+  HYDRATE_ID,
+  ORG_LOCATION_ID,
+  SLOT_NODE_ID,
+  TEXT_NODE_ID,
+  XLINK_NS,
+} from '../runtime/runtime-constants';
 import { cloneAttributes } from './attribute';
 import { NODE_TYPES } from './constants';
 import { type MockDocument } from './document';
@@ -274,6 +281,21 @@ function* streamToHtml(
             }
 
             for (let i = 0; i < childNodeLength; i++) {
+              /**
+               * In cases where a user would pass in a declarative shadow dom of a
+               * Stencil component, we want to skip over the template tag as we
+               * will be parsing the shadow root of the component again.
+               *
+               * We know it is a hydrated Stencil component by checking if the `HYDRATE_ID`
+               * is set on the node.
+               */
+              const sId = (node as HTMLElement).attributes.getNamedItem(HYDRATE_ID);
+              const isStencilDeclarativeShadowDOM = childNodes[i].nodeName.toLowerCase() === 'template' && sId;
+              if (isStencilDeclarativeShadowDOM) {
+                yield `\n${' '.repeat(output.indent)}<!--r.${sId.value}-->`;
+                continue;
+              }
+
               yield* streamToHtml(childNodes[i], opts, output);
             }
 
diff --git a/test/end-to-end/src/components.d.ts b/test/end-to-end/src/components.d.ts
index 64e705faa31..5989dbb0e24 100644
--- a/test/end-to-end/src/components.d.ts
+++ b/test/end-to-end/src/components.d.ts
@@ -100,6 +100,10 @@ export namespace Components {
         "someMethodWithArgs": (unit: string, value: number) => Promise<string>;
         "someProp": number;
     }
+    interface NestedCmpChild {
+    }
+    interface NestedCmpParent {
+    }
     interface PathAliasCmp {
     }
     interface PrerenderCmp {
@@ -334,6 +338,18 @@ declare global {
         prototype: HTMLMethodCmpElement;
         new (): HTMLMethodCmpElement;
     };
+    interface HTMLNestedCmpChildElement extends Components.NestedCmpChild, HTMLStencilElement {
+    }
+    var HTMLNestedCmpChildElement: {
+        prototype: HTMLNestedCmpChildElement;
+        new (): HTMLNestedCmpChildElement;
+    };
+    interface HTMLNestedCmpParentElement extends Components.NestedCmpParent, HTMLStencilElement {
+    }
+    var HTMLNestedCmpParentElement: {
+        prototype: HTMLNestedCmpParentElement;
+        new (): HTMLNestedCmpParentElement;
+    };
     interface HTMLPathAliasCmpElement extends Components.PathAliasCmp, HTMLStencilElement {
     }
     var HTMLPathAliasCmpElement: {
@@ -427,6 +443,8 @@ declare global {
         "import-assets": HTMLImportAssetsElement;
         "listen-cmp": HTMLListenCmpElement;
         "method-cmp": HTMLMethodCmpElement;
+        "nested-cmp-child": HTMLNestedCmpChildElement;
+        "nested-cmp-parent": HTMLNestedCmpParentElement;
         "path-alias-cmp": HTMLPathAliasCmpElement;
         "prerender-cmp": HTMLPrerenderCmpElement;
         "prop-cmp": HTMLPropCmpElement;
@@ -507,6 +525,10 @@ declare namespace LocalJSX {
     interface MethodCmp {
         "someProp"?: number;
     }
+    interface NestedCmpChild {
+    }
+    interface NestedCmpParent {
+    }
     interface PathAliasCmp {
     }
     interface PrerenderCmp {
@@ -564,6 +586,8 @@ declare namespace LocalJSX {
         "import-assets": ImportAssets;
         "listen-cmp": ListenCmp;
         "method-cmp": MethodCmp;
+        "nested-cmp-child": NestedCmpChild;
+        "nested-cmp-parent": NestedCmpParent;
         "path-alias-cmp": PathAliasCmp;
         "prerender-cmp": PrerenderCmp;
         "prop-cmp": PropCmp;
@@ -609,6 +633,8 @@ declare module "@stencil/core" {
             "import-assets": LocalJSX.ImportAssets & JSXBase.HTMLAttributes<HTMLImportAssetsElement>;
             "listen-cmp": LocalJSX.ListenCmp & JSXBase.HTMLAttributes<HTMLListenCmpElement>;
             "method-cmp": LocalJSX.MethodCmp & JSXBase.HTMLAttributes<HTMLMethodCmpElement>;
+            "nested-cmp-child": LocalJSX.NestedCmpChild & JSXBase.HTMLAttributes<HTMLNestedCmpChildElement>;
+            "nested-cmp-parent": LocalJSX.NestedCmpParent & JSXBase.HTMLAttributes<HTMLNestedCmpParentElement>;
             "path-alias-cmp": LocalJSX.PathAliasCmp & JSXBase.HTMLAttributes<HTMLPathAliasCmpElement>;
             "prerender-cmp": LocalJSX.PrerenderCmp & JSXBase.HTMLAttributes<HTMLPrerenderCmpElement>;
             "prop-cmp": LocalJSX.PropCmp & JSXBase.HTMLAttributes<HTMLPropCmpElement>;
diff --git a/test/end-to-end/src/declarative-shadow-dom/nested-child-cmp.tsx b/test/end-to-end/src/declarative-shadow-dom/nested-child-cmp.tsx
new file mode 100644
index 00000000000..bc6061d6fad
--- /dev/null
+++ b/test/end-to-end/src/declarative-shadow-dom/nested-child-cmp.tsx
@@ -0,0 +1,15 @@
+import { Component, h } from '@stencil/core';
+
+@Component({
+  tag: 'nested-cmp-child',
+  shadow: true,
+})
+export class NestedCmpChild {
+  render() {
+    return (
+      <div class="some-other-class">
+        <slot></slot>
+      </div>
+    );
+  }
+}
diff --git a/test/end-to-end/src/declarative-shadow-dom/parent-cmp.tsx b/test/end-to-end/src/declarative-shadow-dom/parent-cmp.tsx
new file mode 100644
index 00000000000..144ebbeac51
--- /dev/null
+++ b/test/end-to-end/src/declarative-shadow-dom/parent-cmp.tsx
@@ -0,0 +1,15 @@
+import { Component, h } from '@stencil/core';
+
+@Component({
+  tag: 'nested-cmp-parent',
+  shadow: true,
+})
+export class NestedCmpParent {
+  render() {
+    return (
+      <div class="some-class">
+        <slot></slot>
+      </div>
+    );
+  }
+}
diff --git a/test/end-to-end/src/declarative-shadow-dom/test.e2e.ts b/test/end-to-end/src/declarative-shadow-dom/test.e2e.ts
index b3d1ef54a01..5159bce3e75 100644
--- a/test/end-to-end/src/declarative-shadow-dom/test.e2e.ts
+++ b/test/end-to-end/src/declarative-shadow-dom/test.e2e.ts
@@ -319,4 +319,43 @@ describe('renderToString', () => {
       expect(color).toBe('rgb(0, 0, 0)');
     });
   });
+
+  it('does not render the shadow root twice', async () => {
+    const { html } = await renderToString(
+      `
+      <nested-cmp-parent>
+        <nested-cmp-child custom-hydrate-flag="" s-id="3">
+          <template shadowrootmode="open">
+            <div c-id="3.0.0.0" class="some-other-class">
+              <slot c-id="3.1.1.0"></slot>
+            </div>
+          </template>
+          <!--r.3-->
+          Hello World
+        </nested-cmp-child>
+      </nested-cmp-parent>
+    `,
+      {
+        fullDocument: false,
+        prettyHtml: true,
+      },
+    );
+    expect(html).toBe(`<nested-cmp-parent custom-hydrate-flag="" s-id="1">
+  <template shadowrootmode="open">
+    <div c-id="1.0.0.0" class="some-class">
+      <slot c-id="1.1.1.0"></slot>
+    </div>
+  </template>
+  <!--r.1-->
+  <nested-cmp-child custom-hydrate-flag="" s-id="2">
+    <template shadowrootmode="open">
+      <div c-id="2.0.0.0" class="some-other-class">
+        <slot c-id="2.1.1.0"></slot>
+      </div>
+    </template>
+    <!--r.2-->
+    Hello World
+  </nested-cmp-child>
+</nested-cmp-parent>`);
+  });
 });