vboxmanage import shows 2 identical Hard disk images - virtual-machine

Question

I have created ova file using this command
> vboxmanage export asr_3.7.0 --output
> /home/asr/workspace/asr/virtualbox/asr-sandbox-3.7.0.ova --vsys 0
> --product 'My Sandbox' --version 3.7.0 --description 'asr Sandbox for Release 3.7.0'
before this i perform vmdk to vdi conversion for disk compression.
now when i import this ova file, it shows that it is having 2 hard disk images with identical size as shown in step 17 and 18.
vboxmanage import asr-sandbox-3.7.0.ova
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%
Interpreting /home/ankit/asr-sandbox-3.7.0.ova...
OK.
Disks: vmdisk2 68719476736 -1 http://www.vmware.com/interfaces/specifications/vmdk.html#streamOptimized asr-sandbox-3.7.0-disk1.vmdk -1 -1 vmdisk3 68719476736 -1 http://www.vmware.com/interfaces/specifications/vmdk.html#streamOptimized asr-sandbox-3.7.0-disk2.vmdk -1 -1
Virtual system 0:
0: Suggested OS type: "Ubuntu_64"
(change with "--vsys 0 --ostype <type>"; use "list ostypes" to list all possible values)
1: Suggested VM name "dtbox_3.7.0"
(change with "--vsys 0 --vmname <name>")
2: Product (ignored): asr Sandbox
3: Vendor (ignored): asr
4: Version (ignored): 3.7.0
7: Description "asr Sandbox for RTS Release 3.7.0"
(change with "--vsys 0 --description <desc>")
8: Number of CPUs: 1
(change with "--vsys 0 --cpus <n>")
9: Guest memory: 4096 MB
(change with "--vsys 0 --memory <MB>")
10: Sound card (appliance expects "", can change on import)
(disable with "--vsys 0 --unit 10 --ignore")
11: USB controller
(disable with "--vsys 0 --unit 11 --ignore")
12: Network adapter: orig NAT, config 3, extra slot=0;type=NAT
13: CD-ROM
(disable with "--vsys 0 --unit 13 --ignore")
14: IDE controller, type PIIX4
(disable with "--vsys 0 --unit 14 --ignore")
15: IDE controller, type PIIX4
(disable with "--vsys 0 --unit 15 --ignore")
16: SATA controller, type AHCI
(disable with "--vsys 0 --unit 16 --ignore")
17: Hard disk image: source image=asr-sandbox-3.7.0-disk1.vmdk, target path=/home/asr/VirtualBox VMs/asr_3.7.0/asr-sandbox-3.7.0-disk1.vmdk, controller=16;channel=1
(change target path with "--vsys 0 --unit 17 --disk path";
disable with "--vsys 0 --unit 17 --ignore")
18: Hard disk image: source image=asr-sandbox-3.7.0-disk2.vmdk, target path=/home/asr/VirtualBox VMs/asr_3.7.0/asr-sandbox-3.7.0-disk2.vmdk, controller=16;channel=0
(change target path with "--vsys 0 --unit 18 --disk path";
disable with "--vsys 0 --unit 18 --ignore")
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%
Successfully imported the appliance.
I am not sure why i am seeing 2 disks there.
Forgive me for the silly mistaks, i am new to it.

Answer 1

Actually when I created the VM, it already had vmdk disk attached to it.
later i created vdi disk from the vmdk and then attached it to my vm.
I did not detached the vmdk from my VM which was the reason I had two identical disks on my VM.