Copy Item Cost from one cost type to other cost type

Hi,

Frozen cost is with Zero value and i am trying to copy this Frozen cost (Cost type1) with zero value to another Standard cost (Cost type 2). when i ran the "Copy item cost" program with Parameter "Merge and Update existing costs" i cannot see the record for another cost (Cost type 2) with zero value at item cost summery form.

but if i choose the second parameter "New Information Only" i can see both records Frozen cost (Cost type1) and another Standard cost (Cost type 2) with zero unit cost

so my question is why can't we see the Cost type 2 if i go with Parameter "Merge and Update existing costs"