Batch Data Entry via form with unique field (1 Viewer)

Hello,

I am after a solution that will let me use a form to perform a batch data entry into a single table.

Example

Site: 123456
Serial: 78945
Date: 08/02/2016
Multi: Y
Serial_2: 99565
Serial_3: 54554
Serial_4:

What I am trying to achieve is where Multi = Y it will create an entry for Serial and then another entry for Serial_2 (but it populates Serial and blanks out Serial_2) and the same for Serial_3

attached is the example I am trying to achieve using a single form.

Why not making 2 tables ?
As far as I can see from your example, you have duplicated data. It will make the entry less complicated.

The data would not be duplicated as the Serial would make the record unique. The data entry would be happening on the form meaning the user never sees the table. I just cant think of/find anywhere on google to help me perform that batch process of records. Users currently do this activity one at a time just looking for a quick way where they only have to fill in 1 record and then supply the other Serials they want to create the same record for.

I can do this in SQL no problem. Need the form to do this at the front end.