IFRS 16 Opening Balance Migration

We are implementing IFRS 16 and the customer has open balance in ROU and Lease Liability. Customer so far used to depreciate ROU and take it to Accumulated Depreciation Account. Below are the closing balance given to migrate:

ROU -- Dr--500000

Lease Liability --Cr--300000

Accumulated Depreciation --Cr--200000

Understand, we migrate the lease with the remaining payment term. This will eventually create accounting as ROU Dr and Lease Liability Cr (both will be equal). But it does not tally with the customer account balance of ROU and the difference is lying in Accumulated Depreciation Account.

Can you please suggest the best practice migrate the on going leases in compliance with IFRS 16. Do we have any mechanism to have ROU and Lease Liability different and take the difference to accumulated depreciation.