Started new job - got taxed double

Hi,

I've got a problem here my tax code is "1000l n", I started a new job on 3rd 2015 and my first pay day is tomorrow, I checked my payslip from my previous employer and it's diffrent:

New job tax code "1000L N"
Old job "1000L 0"

What is the different, I also handed in my p45, is that a emergency tax code with I be due some extra cash next month then ?

Help will be appreciated.

Thanks