Mass transfer of inventory and lot information

Hello,

We have manually created item master records to hold rework inventory (to keep it totally separate from finished good items).  Essentially we took the existing item master (i.e. SN1000003673) and created the same with a "R" at the end of it (i.e. SN1000003673R).

Now we are looking for a way to do a mass transfer of existing on-hand quantities and lot information from the standard item to the "R" item.  I thought of doing a reclassification (P4116) but I'm getting new lot dates even though I'm using an existing lot.  How can I prevent that or is there a better way to do this?  Do I need to somehow add the lot to the new item ahead of time?