First: multiple hits per plate. This test simply represents the harsh realities of war. Rarely, if ever, are tank battles one on one encounters where only one shot is fired. Usually you are facing a battery of guns or a platoon of tanks that will all fire at the same time, and they will do without being gentlemen and letting the other party reload. For instance, here are photos of tanks caught in an ambush.
Now for the next part: removing components before testing. You can see that some components are missing from the vehicles above: guns, vision blocks, etc. This is also caused by harsh reality. When you capture an enemy vehicle, everyone wants a piece: the artillerymen, the optics scientists, the electricians, the mechanics. By the time the tank reaches the range, odds are it will be stripped of any components other than the hull, since nothing inside will survive the rigorous testing displayed above. Sometimes you don't even get an entire tank. Nevertheless, this is another reality of life and simply how everyone tested.