I guess this is something I couldn't practice anyway. My children have all slept through the night by a month old. The ones who have the duplication have all had to be woken from birth to be fed as they don't cry a lot. In fact my now 5 year old had to be timed for everything because she didn't cry EVER! Now a few of them have sleep disorders from the dup and have to take melatonin
if by sleep training you mean crying it out in the crib...we def did it...and worked great only about a week or so...then he got pnuemonia and started wanting to be rocked to sleep that lasted about 6-8months and then we just started over again now as soon as he hears its night night time he heads for the stairs and waits for one of us to take him up and we lay him down say i love you and night night and he falls right to sleep...i mean he's almost 2 so he has his bad nights but 99% of the time he does great.