There are many ways to clone VMs from one Azure Resource Group to another. Here is one example that are using Azure Snapshots. The VMs, to clone, has to belong to the same Azure Region as where the copy should be created and has to use managed disks.
To get going with the script, download or copy it from my GitHub account. It works perfect in Azure Cloud Shell for PowerShell as well as in a Azure Automation Runbook. Just remember to upgrade the modules before running it.
Here is a screenshot from a ready clone from Resource Group myvms-rg.