Issue with Pathfinder "Merge" tool

[CryptoZooeez]

After trying to Merge using the pathfinder menu, I am having a ton of anchor points showing up as before the merge there was nowhere as many. My suspition is that the overlapping expanded strokes are giving this undesired effect. Is there anyway to avoid this or get around this happening? Here is a detailed video of what I am doing along with the native file for you to experement with. Any thoughts?

[Monika Gause]

There are duplicate paths. Exact copies of paths on top of each other that cause this. 

If you get rid of them first, then it will work. You could build your art differently, using Live paint instead of Divide or the shapebuilder tool that you used to create that light belly. 

To fix this you could erase one set of these duplicates after expanding the strokes and fills.