Duplicate disk_used_percent metrics

I have CloudWatch Agent installed on Ubuntu instances, set to monitor disk_used_percent for two paths ("/", and "/mnt/data")

These are Nitro instances, so the nvme device names can change after reboot (e.g. nvme0n1p1 can become nvme1n1p1). To deal with the nvme device name changes, I use "aggregation_dimensions" leaving out the "device" dimension in the CloudWatch Agent config. This works, but I get duplicate metrics being sent to CloudWatch.

In the CloudWatch console, I see disk_used_percent metrics for both paths listed under
CWAgent > InstanceId, fstype, path

But I also see disk_used_percent metrics for both paths listed under
CWAgent > InstanceId, device, fstype, path

How can I deal with the changing device name, but not send duplicate metrics? Thanks!

Here is my CloudWatch Agent config:

{
  "metrics": {
    "append_dimensions": {                      
      "InstanceId": "${!aws:InstanceId}"
    },
    "aggregation_dimensions" : [["InstanceId","fstype","path"]],
    "metrics_collected": {
      "disk": {
        "measurement": [
          "disk_used_percent"
        ],                
        "resources": [
          "/",
          "/mnt/data"
        ]
      }
    }
  }
}