Too bad about your peashooter, scooter.

There are conflicting reports about the time of flight before failure of the early morning launch of the North Korean long range missile.
News reports have varied from 30 seconds to more than 90.
Were it in the range of a 45-60, there is a possibility that there was a failure to lighting the second stage. Less than that, a likely failure in the first stage or the attitude control.

The sooner the failure, the better it is for everyone other than the NorKs since the less of a failure that they could monitor, the less likely it is that they could correct its' flaws.

Lighting of a stage in flight has always been a difficult problem to solve. The longer it takes for them to sort it out the better it is for the people threatened by North Korea, and its' likely clients such as Iran.

There could have been many reasons for firing 2 (some reports say 5) medium range missiles with the Taepodong.
It may simply be more cost effective.
They could have been trying make showstopping vaudevillian video agitprop.
They might have wanted to integrate a excercise simulating wartime operation.
They might have had so little confidence in the new missile, that they wanted to at least present the Japanese, South Koreans, and the rest of world with the barrage to limit the deflated threat of a botched launch.

But as with everything about the hermit kingdom of North Korea, one can only watch and speculate.