If the imported file is an SKP file, then 3DXchange can generate the corresponding Back Face for each node. You may see them listed in the Scene Tree.
Load the SKP file.
You will see the front and back faces listed in the Scene Tree.
The Total Faces Count will be high since the back faces are all included.
In the Main Menu, select Edit/Exclude SKP Back Faces.
All the back faces will be excluded without affecting the look of the model.
The total face count decreases by half.
Click the Hide Excluded
button under the scene tree,
in order to clear the display of the scene tree.
Note:
If you need to assign different textures to both sides of a polygon, such as a wall, then you may need to do the same to the back side node.
If there is no need for the camera to view the inside of the model, then it is highly recommended that you exclude the back sides during export.
Please refer to https://www.reallusion.com/iclone/3dx_BackFaces.asp for more details about Back Faces.