For now I have R53 record for APM server which is writing data to ES.
I want to create another ES cluster and I want to check performance first for new cluster. For that - I want to create another instance with APM server, which will be use new ES endpoints.
Is it possible to send the same data from R53 to old and new APM server instances to have the same data in ES for performance tests?
No, that's not how DNS works.
DNS is used for the initial lookup of an IP address for a given domain name.
It may return multiple IPs, but the client decides which of these IPs to use and usually only connects to one of them.
There is a way to do traffic mirroring with the VPC, I'm not sure if that helps you. Check out the docs for VPC Traffic Mirroring.