Chugman,
I prefer to have different numbers. I had MTH 4 bay hopper cars stripped, painted and renumbered a couple of years ago. I used different numbers on each car & used birthdays, anniversary date, address's etc. on each car. I recently ordered 4 of MTH's 3 car hoppers sets in CSX which at the moment I think I will leave as is when I run them.
Joe B.