Parse.Object.saveAll can result in duplicate objects

New Issue Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.
• I can reproduce the issue with the latest versions of Parse Server and the Parse JS SDK.

Issue Description

this issue has been specifically created to reference in this PR

Parse.Object.saveAll uses the /batch endpoint

if you have a large batch of large objects that are being saved via saveAll, and the network quality is very slow, it can happen that the initial request times out, and will therefore be automatically retried. However, some of the objects in the first batch may have already been successfully saved - but then the second retry would result in duplicate objects being created.

Steps to reproduce

Watch this Loom

Actual Outcome

duplicate objects created

Expected Outcome

no duplicate objects

Environment

JS SDK used in web client, over spotty networks

Server

• Parse Server version: any
• Operating system: browser
• Local or remote host (AWS, Azure, Google Cloud, Heroku, Digital Ocean, etc): remote

Database

• System (MongoDB or Postgres): mongo
• Database version: any
• Local or remote host (MongoDB Atlas, mLab, AWS, Azure, Google Cloud, etc): remote

Client

• Parse JS SDK version: latest

Logs

Start with Parse.Object.saveAll and its /batch requests, then review the referenced Parse JS SDK pull request #1432 and the linked reproduction video. Done means retries on slow networks no longer create duplicate objects; the issue names no source files or tests.