Here is the entry for codeine (S3) in the SUSMP:
CODEINE when:
(a) not combined with any other opiate substance;
(b) compounded with one or more other therapeutically active substances, of which not more
than one is an analgesic substance:
(i) in divided preparations containing 12 mg or less of codeine per dosage unit; or
(ii) in undivided preparations containing 0.25 per cent or less of codeine;
(c) labelled with a recommended daily dose not exceeding 100 mg of codeine; and
(d) in packs containing not more than 5 days of supply at the maximum dose recommended
on the label,
except when included in Schedule 2.
Emphasis mine. Ok, so it says 12mg of codeine per tablet; have a look at the nearest packet of pain tablets (like me, I assume you have plenty at hand) and have a look at the ingredients listed. Codeine phosphate and paracetamol/ibuprofen.
The codeine is ionically bound to the phosphate anion (so it is present as a salt). Note that the SUSMP doesn't specify 12mg of codeine as a salt, just 12mg of codeine itself. So these new Mydol have 15mg of codeine phosphate per tablet, however if you subtract the weight of the phosphate you end up with less then 12mg codeine per tablet, and it is still a 5 day supply. This same principle is why Nurofen + can have 12.8mg per tablet, I just didn't really think about that before because it was only .8mg over.
Does that make sense? I can do the math to figure out the exact codeine content if anyone is interested.
Also, regarding the two boxes, the schedule doesn't say that pharmacies can't sell two boxes just that packets can only have a 5 day supply. Most pharmacies won't sell you two at once, however it depends on the pharmacist and I have a friend who can sometimes charm his way into getting two big packets and a big bottle of Rikodeine. :D