Central Air Ducts

[ethyrdude]

This may have been discussed elsewhere however if it was I couldn't find it.  In any case, I was messing around with the air ducts from the LN ep and I noticed something I consider very weird.  4 of the ducts can be found in decor/miscellaneous, the other 4 you have to use buydebug on to find them in the miscellaneous section there.  Now why would anyone think that would be a good idea to split them up like that?