A developer is investigating an issue in part of a company ' s application.

A developer is investigating an issue in part of a company ' s application. In the application messages are sent to an Amazon Simple Queue Service (Amazon SQS) queue The AWS Lambda function polls messages from the SQS queue and sends email messages by using Amazon Simple Email Service (Amazon SES) Users have been receiving duplicate email messages during periods of high traffic.

Which reasons could explain the duplicate email messages? (Select TWO.)