---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/35134#article
headline: "35134: `Messages` array contains duplicate `To` numbers."
url: https://www.twilio.com/docs/api/errors/35134
inLanguage: en
dateModified: 2026-05-06T13:22:30.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 35134: \`Messages\` array contains duplicate \`To\` numbers.

Log Type: APPLICATION

Log Level: ERROR

## Description

This error occurs when your request includes the same destination more than once in the Messages array. Bulk messaging requests use a recipient list, and each recipient entry must be unique.

### Possible causes

* The same phone number or channel address appears more than once in the request payload.
* Recipient values were not normalized to a consistent format before you built the request, which can cause the same destination to be submitted more than once.

### Possible solutions

* Remove duplicate destinations before you send the request. Ensure each recipient appears only once in the Messages array.
* Normalize phone numbers to E.164 or use a consistent channel address format before you compare and deduplicate recipients.
* Validate and format phone numbers before sending so you can deduplicate against a single canonical value. Use Lookup if you need to confirm the format of each number.

#### Additional resources

* [Getting started with the Twilio Communications API](/docs/bulk-messaging/getting-started)
* [Formatting and Validation](/docs/lookup/v2-api/formatting-validation)
* [Formatting International Phone Numbers](https://help.twilio.com/articles/223183008-Formatting-International-Phone-Numbers)