The Master Sword was the Blade of Evil's Bane given power by the Goddesses and Sages of Old Hyrule, and in the ST timeline, is currently embedded into Ganon's skull. The Lokomo Sword was stated to be a sword empowered by the spirits of New Hyrule. They serve the same purpose and come from similar origins, but they are two different swords.
These are just lame copies of the master sword... They are basically swords to use to defeat the enemies in their own homeland, like in ST and PH.
Nintendo are just to lazy to create a new type of sword, and instead makes a copy of the MS.
This pretty much sums it up. It's not possible for the Master Sword to ever come back on the AT.