docData observable stream emits identical object values multiple times in a row

### Version info

**Angular:** ^18.0.0

**Firebase:** ^10.13.0

**AngularFire:** ^18.0.1

**Other (e.g. Ionic/Cordova, Node, browser, operating system):**

"@ionic/angular": "^8.0.0",

Tested on MacOS Chrome, but reproducible elsewhere. Else let me know.

### How to reproduce these conditions

Simply press the update button after strating this project, it will update the game entity and make it emit twice:
https://github.com/folsze/firebase-observable-double-emission

here is a related stackoverflow post that I created:

https://stackoverflow.com/questions/78891192/firebase-docdata-stream-emits-identical-object-values-multiple-times-in-a-row

**Steps to set up and reproduce**

run with package json npm run

then simply press the update button, it will update the game entity and make it emit twice:

### Debug output

** Output from `firebase.database().enableLogging(true);` **
<- I have no idea what this is suppoed to do for me. I added this but receive no logs:

import { enableLogging } from '@angular/fire/database';

enableLogging(true);

### Expected behavior

It only emits once

### Actual behavior

it emits multiple times (twice currently for this simple scenario):

從連結的重現專案 firebase-observable-double-emission 及其 package scripts 開始；執行它並按下更新按鈕，以觀察 docData 串流。結合提供的 Stack Overflow 討論和記錄說明作為背景，將重複的相同 emission 與預期的單次 emission 進行比較。

由索引模型根據 Issue 內容生成。