When did Australia Post add extra numbers to tracking & why are they not consecutive?

Used to be 15 numbers and you could copy and paste, just changing the last 2 or 3 every time you entered. 

Today I posted 8 parcels.  The first 10 numbers were consistent, then the following 13 are jumbled differently every time.  What a pain!

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I am guessing due to the big increase and delays in parcels, AP has needed to expand their options re tracking numbers.