What are the special steps and care to be taken in Fixed asset data migration into SAP system especially when Profit center accounting is active?

Data migration is slightly different from a normal transaction which
happens in Asset accounting module.
Normally, in asset accounting the day to day transactions is posted with
values through FI bookings and at the same time the asset reconciliation
is updated online realtime. Whereas In data Migration the asset master
is updated with values through a transaction code called as AS91. The
values updated on the master are Opening Gross value and the
accumulated depreciation. The reconciliation GL account is not
automatically updated at this point of time.

The reconciliation accounts (GL codes) are updated manually through
another transaction code called as OASV.

If profit center is active, then after uploading assets through AS91 you
should transfer the asset balances to profit center accounting through a
program.

Thereafter you remove the Asset GL code (reconciliation accounts) from
the 3KEH table for PCA and update the Asset reconciliation account (GL
code) through OASV.

After this step you again update the Asset reconciliation account in the
3KEH table.

The reason you remove the Asset reconciliation code from 3KEH table is
that double posting will happen to PCA when you update the Asset
reconciliation manually.