50 heightmap textures?! Mamma mia...
But if you want to easily import an area into a new area (completely, not just textures, also including models and environmental settings), you would want to use the Import option. This can be slow if you use a lot of resources.
To do this:
Go into the area you want to edit. [Area_A]
Right-click the area which you would like to import [Area_B]
Press Import
Press OK
Wait.... Wait a bit longer...
Now travel to another area (doesn't matter). [Area_C]
Wait...
Travel back to the edit instance of the area you were editing. [Area_A]
Voila, now you should have an exact duplicate of the area in your new area. [Area_B replicated in Area_A]
[Of course, you could also just make an Area_D which only has a heightmap, and add the 50-ish textures; it will thus only import the textures + single heightmap; making it a "fresh" area, but with the added textures

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