I'm in the process of buying a large collection of US & World coins. I've worked my way through the US and am now looking at the Australian coins. At the bottom of the box there were two 1923 half pennies. I know that these are key dates and there are fakes. Beyond that I'm totally lost. Both of these coins are medal alignment and 25.5 mm diameter. The first coin weighs 5.67 grams and the second weighs 5.55 grams. I'm hoping these pictures are good enough to get opinions on authenticity and possibly grades.