No, there aren’t any policy for Aerospike to write more than one copy to the device. Aerospike only keeps one live copy on any node regardless of your configuration.
I haven’t used the nvme command before nor am I aware how it could interpret the amount of space Aerospike is using. It is possible that Aerospike has written to the 2 GiB offset which this tool interprets as 2 GiB used - but this doesn’t mean that 2 GiB are currently in use by Aerospike.
For updates, Aerospike uses a copy on write. The prior copy is eventually returned back to the free pool when the block becomes eligible for defrag. I’d recommend learning more about the defragmentation process.