It is important to note that once gltf is exported it shouldn't be renamed because it won't work when uploaded to Moicon.

An example would be, if you exported files named model.gltf and model.bin, and then renamed them to model(1).gltf and model(1).bin, would result in an error (this can happen often when someone sends you many files with the same name and they are being downloaded to the same directory).

In order to resolve this problem, you can either remove (1) from it's name or edit model(1).gltf in a text editor, search for 'model.bin' and replace it's path with 'model(1).bin', or if you can, simply export the files again from your 3D software with the desired name.

3D software such as blender tell you what happens to the 3D assets after exporting, it's common:

The glTF format requires discountinous normals, UVs, and other vertex attributes to be sotred as separate certicies, as required for rendering on typical graphic hardware. This option attempts to combine co-located vertices where possible. Currently cannot combine verts with different normals.