The two dollar coin denomination (written as $2) was introduced in Australia in 1988, replacing the earlier banknotes. The original reverse design by Horst Hahne on circulating coins has not been changed since its introduction. The denomination is also often used to issue circulating commemorative coins with various reverses.
Apart from the circulating coinage, both the Royal Australian Mint and the Perth Mint have extensive programs issuing $2 coins for collectors (Non-Circulating Legal Tender, or NCLT), such as this one.
In 2006, the Royal Australian Mint produced some for mint sets (brilliant uncirculated coins and proofs), celebrating the 40th anniversary of the decimal currency. The silver proofs (only) have Her Majesty's "Second Portrait" (by Arnold Machin), which was last used in Australia in 1984.
The 8-coin Fine Silver Proof 2006 Year Set contains 1 cent, 2 cents, 5 cents, 10 cents, 20 cents, 50 cents (round), $1 and $2 coins - all with the Queen's Second Portrait by Arnold Machin, as the initial decimal coins released in 1966.
The coins were made of 99.9% silver. No coins of this type were released into circulation.