Asset replaced by a new one

Hi expert,

We are facing the situation below:

Asset are replaced  free of charge one by the vendor due to guarantee. For some of them, the depreciation is already started.

Lets say asset bought in 01/ 2013 and deprecation started at this date.

In 10/2013, the vendor replaced it by a new one.

Could you tell me which is the best practice to manage the old and the new asset please?

Thanks.

Regards.

A.