Contrasting personalities

When we initially conceived our second baby, one of the first things that came to my mind was 'We already have one and we have gone through many ups and downs with the first one. Now that we have learnt our lessons , How hard can the second one be?'. I am a programmer by profession. That's probably why I must have thought like that.
But Oh boy! We just can't believe how different our second one is from the first one. Granted they look similar. But they are 2 different personalities. Life always seems to present us with challenges all the time. But we are thoroughly enjoying it.