For in-place migration, it is documented in the below link
https://docs.vmware.com/en/VMware-NSX-T-Data-Center/3.2/migration/GUID-7BD2A0E9-2EB3-4585-8F04-D6F18...
Prerequisites
If you are doing lift and shift, you can use the same or different VLAN, just ensure there are no overlapping IPs(IP Range)
Cheers,
Sree | VCIX-5X| VCAP-5X| VExpert 6x|Cisco Certified Specialist
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