Hello,
I think these coinse are the same:
https://en.numista.com/catalogue/pieces75798.html
https://en.numista.com/catalogue/pieces75361.html
The weight differs, but the bank of PNG talks just from 1 non-colorized coin:
http://www.bankpng.gov.pg/announcement/notice-of-issuance-of-commemorative-currencies-2015/
Regards
Peter