Caution: Change documents and local tables are being copied

What causes this issue?

You have selected a copy profile with change documents. This is only
useful for recreating a production client if the numbers of the target
and source clients match.
If the clients are not the same, the change documents are worthlesss
and can even crash application transactions.
This can also greatly increase runtime because the change document
tables can be very large.
Local tables (delivery class 'L') und system tables (delivery class
'W') are copied to guarantee complete recreation of the client. If the
target and source systems are not the same, this local data can be
unusable and cause problems.

How to fix this error?

The copy profile used is only for recreating a client.
Ensure that the target and source client numbers match, or choose
another copy profile.

Error message extract from SAP system. Copyright SAP SE.