In Animal Farm, what does the alteration of the first commandment mean?

The First Commandment reads, "Whatever goes on two legs is the enemy."  At the end of the novel, the pigs begin walking on two legs.  Therefore the commandment must be changed in their favour. 

In the course of the novel, the commandments are amended to and changed without the consent of the populace.  Generally, an animal will go to the barn wall to check what the commandment says and find it altered.  This shows that someone (the pigs) are in power and that they have the power to change what was once considered by the whole of the Animal Farm to be unalterable and agreed upon by all.

At the end of the novel, only one commandment is there and it says, "All animals are equal, but some are more equal than others."  At the end of the day, all animals are equal but the pigs are 'more' equal.  This is the best example of 'double speak' available.  The less intelligent animals will not think to question this idea.  But in effect, in equality is inequality and the animals are in the same state as they were with Mr. Jones.  The pigs are the new aristocracy.