Two Delta files are being created while taking the snapshot of a VM.

Products

• VMware vSphere ESXi

Issue/Introduction

• Two delta files getting created while taking snapshots with application quiescing.

Environment

• VMware vSphere ESXi

Cause

Quiesce snapshots are a special variant of VM snapshots that aims at achieving consistent application state. This involves VMware tools in the VM as well as an infrastructure such as Volume Shadow Copy Service  in the Windows OS.

Resolution

This is as per design but can be changed following the steps mentioned in the below KB, post which only 1 delta file will be created:
Disabling Application Level Quiescing During Snapshots of Virtual Machines