The Mysterious System Part I

I was here to dismantle the customer's system and them replace it with our own. Then we're to take their original system and keep it in storage for a few days until their new office is ready. Nothing weird about that until my Boss pointed something out.....

This is their original system, still mounted on the wall.
What I am going to do is, to take it down, and put ours
onto the wall. And so, I have to do this in less than an
hour. Which is not a problem if I was ten years younger.
For those who know, look at the second cabinet.

Something funny, right? How can a Base cabinet
be used to replace an actual expansion cabinet?

Anyway, I did not think much about it since I have
less than an hour left to complete this. I have to work
fast as everyone would be back from their lunch hour.

While I was cleaning up, I did notice the second
cabinet's metal surface was polished. Hmm......