autocad is creating new layers by itself

This is what is happening,

for example, i have a layer for dimenisioning called, 'DIM.' I'm not sure when it happens but AutoCad creates new layers that are called: DIM @ 12, DIM @16, DIM @ 18, DIM @ 128....It does this for different layers as well. I'm just curious has anyone run into this before? There must be some significance of Autocad adding a @ # at the end of the layers name. 

It then changes certain blocks from the regular layer, to these new ones. It doesn't affect any block consistently. So one block 'A' is changed to the new layers, but the other block 'A' is not changed.

The only thing I did differently for this drawing set was used dxfout/dxfin to purge dgn files out of my drawing, any possiible connection there?

Any help would be appreciated.

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