What is that on the T-34/85

I hope my question is not too specific or weird. I have just finished my DML 1/35 T-34/85. When I compared it with a Tamiya 1/35 T-34/85, I discovered something different. If you look at the frontal hull on the DML one, you will see, between the driver's hatch entrance and the spare track, there is a piece of slim metal welded onto the hull. This cannot be found in the Tamiya one. I checked it out in web site and reference books and saw that early T-34 sometime had it sometime not.

Now, my questions are:
1) What is that piece of metal?

2) Which one is right, Tamiya or DML? In the future, if I do other T-34, should I add styrene stripe on it(for Tamiya) or sand it off(for DML)?