What version of ESX are you running? If this is ESXi 5.x, it is normal for a VM to have multiple .vswp files
If this is a lower version ESX, power off the VM's - the .vswp files should be deleted. If there is an unclean shutdown etc, you might have a left over vswp file that you can manually rename or delete and power on the VM back at which point you should see just one vswp file