I spent the last hour reaserching basilisks and iguana's trying to compare the two. First i read 40 inches in lenth, then i looked at the pictures again and noticed there was no way it was inches. I re-read your question to find you had initially typed cm. Okay so you do have the common green basilisk (basiliscuz plumifrons), and they are both females-by the looks of them. They have the circular cap behind their ear, and not the circular cap under the jowl like the green iguana does.
The green basilik(female) reaches nearly 3 feet, but dont be surprised if they only make it to 2--21/2ft. It really depends on the conditions they were kept in before you got them home. I am estimating approx 8-12 months old. They are not the kind of reptile that grows fast on you, unless your feeding them rodents bi-weekly.
Keep in mind reptiles are cold-blooded creatures so they wont grow on ya unless they are kept warm. The warmer they are, the faster they grow and live/but then the faster they die.
Can I ask how much you paid for them? If they truly are basilisks and you paid for 2 iguana's you got a kick ass deal. Iguana's are a lot of work, and if you have two adults together, you will need a room sized enclosure for them. VS basilisks only requiring approx 2x2x4 minimum (feet)
Basilisks are usually much more attractive animals then the iguana's and they reach a handleble size. (sorry its late lots of spellin errors).
Hope this has been some help, keep us posted with some pictures.
Josh.