Is there any way with commands, to have 2 Armories on your house?
No, there is no way to have 2 armories in one house. Hearthfire buildings are collections of disabled world objects that get enabled when built by the player, in order for a second armory to be buildable it would need to have been prepared by Bethesda and included in the DLC.
If you're not satisfied by vanilla and DLC housing options in Skyrim, you should take a look at the available mods - some of them surpass Bethesda's creations in every way.