Maintaining Item Numbers in AX 2012

I have the following scenario,
I’m having Item Number which is currently used in the legacy system and while importing master data to AX 2012, I want to change the existing item number with new one. However I need to have both numbers in AX 2012 for some time for user convenience.
How to address this situation. Any suggestions.
Thanks in advance.

May be you can think of using the “search name”. Input the old item number in the search name and train your users to search the “search name” field also while they are trying to find an item.

Thanks Santosh. That is a good idea.