Imagine a two-room house whose occupants have outgrown it. They decide to solve the dilemma by tacking another room on the back. Great! The siding doesn't quite match - nor does the roof. Some of the existing old-growth trees had to be felled to make the new room fit, and when you're inside, you have to remember to step down and duck a bit as you enter the new room. But hey! The owners still have that extra room! If they decide to put their home on the market, they can advertise it as having three rooms.
Unfortunately, some EHRs are built like this.