Internal Mass - Various types - Issue

I’m not sure this is a bug or that i’m not behaving well.
I want to define two different kinds of internal mass for a zone (i.e. internal walls and furniture). Of course their materials are different.
I’m using the addInternalMass in tandem (twice). One for the furniture and one for the walls. So far, so good.
The issue i’m having is when i look at the IDF. In theory i should receive 2 internal mass in the file. Instead, i’m having four. Two of the are an exact duplicate of the first two. I can’t find in the code where is that happenning.
I’m attaching the basic model and the idf obtained.

I’m missing something?

-A. (555.3 KB)
IntMassIssue.idf (99.2 KB)