Applying the same material to two previously seperate materials combines them, and makes it hard to add different materials later

So, I’m coming from Lumion and try out Twinmotion. I’ve tried now both fbx and datasmith, and I’ve tried importing the model based on hiarchy or materials.

I have maybe 20 exterior walls which has one material on the inside, and another on the outside.

If I apply a material to the exterior side, it applies to all the exterior sides, all good

I then apply a different material to the interior, and it applies to all the interior walls, and exterior walls do not change - still all good.

Now, if I should at any point happen to end up applying the same material on the interior and exterior walls, they are suddenly threated as one.. if I now want to apply a unique material on all the exterior walls, I no longer can. applying anything on the exterior will apply it on the interior as well.

If I instead add material based on object, that will not add it to all surfaces that had the same material on import, but only to the one object I selected..

I’m sure this isnt a shortcomming of the software, but me not knowing how I should do it. What is the way to get this right? Sure I could just make sure to never ever apply the same material to two that should end up being seperate - but while trying things out applying the same material is part of that, and I need to be able to go back and forth - Lumion keeps the imported materials(surfaces) unique forever - and I hope to be able to do this here as well

Whenever I now add a new material I always rename it to what I added it to, and make sure that whenever I’ll add that material to something new I first make a duplicate, rename it - then apply it. that way I keep things separated. It’s more hassle and means I might have 4-5 completely similar materials just to be able to easily change them separately later - so it’s not optimal - but at least it keeps problems away. Still happy to hear if there are better ways to do it :slight_smile: