Uhhhh, the concept of duplicate serial numbers is rather contrary to the very basic premise of a serial number......
 
As to editing them, yes, you can. If they aare attached to a Sales Order line they can be edited in BKSOSER and in SERIAL in maintain DB. If not in SO but on a WO you can edit them in WORECV and in SERIAL. If memory serves, these are the tables to be dealt with for editing.

JFillmore,
We too use serial #s in a way they weren't supposed to be used....But it works GREAT  for us.
 
Heres how:  We rework, recover, fix, repair our customers' widgets.  Over a yr period we might see the same widget 10-20 times.    The cusomer has already named his widgets something like AZ01, AZ02, ...AZ87 etc.
 
Everytime we do something to widget we use the customers number, add the inverted date, and then abbreviate the process.  
 
So when a customer calls and wants to know what we have done to AZ49....we just print the report which would look something like this:
 
w#         y/m/d    process
AZ49 20040113 grind
AZ49 20040203 beari
AZ49 20040228 grind
AZ49 20040411 grind
Az49 20040526 beari
AZ49 20040730 grind
 
We can tell the customer we ground it 4 times since January and put bearings on it twice.  
We are also able to print a neat concise for our customer.  It also very easy to export to an EXCEL spreadsheet.
 
As for editing serials #s,  Idid it a few yrs back thru Maintain database, can't remember the file names though
 
 
 

OK, if you are bringing an item back in that is serialized to do repairs (warranty or whatever), then you need to create a negative 1 quantity SO and select the serial number that the item originally went out under. This will put it back in stock as an on-hand quantity of 1. Do your repairs and such and then send it out again on the SO and that will releive inventory for that serial. WITHOUT using -1, -2, etc.