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

[vintagetrader1]

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!

[7ransparency]

Possibly to prevent incorrect entry, forcing you to double check if the numbers are different.

[davewil1964]

I'm amazed you typed that with a straight keyboard. It's because the numbers are allocated on a first-come, first served basis. And they don't allocate blocks to specific members. If the OP is having to change 10 numbers, the OP is either very infrequent or doesn't realise that the last 11 generally only require a change of check digit.