Already having the PPL has no negatives when it comes to applying. The positives are that you have some prior experience and so can draw on that during the interview perhaps.
There is also the potential to reduce some of the training hours during the basic flying stage when you are out in New Zealand. In return for reducing the hours you receive the cost of the lesson back.
Also, if you have done a trial lesson or begun a PPL, then you have a fairly good idea if this flying lark is actually right for you. Countless people have applied to CTC, done the ground school and never stepped in a light aircraft before. Then when it has come down to it, they have discovered that either they don't like it, or can't handle it.