Thanks Al, but I need a green one.
Tom, Gilbert must have had some pretty savvy marketing people when they made so many variations of a given number. The average train runner probably didn't or doesn't care about color, painted or unpainted, chassis type, truck type, or box stamping variations. On the other hand, Gilbert surly knew that collectors would want all variations so they made many different variations to promote sales. Much like Mattel did and probably still does in their Hot Wheels and Matchbox cars. I know that from my collecting, and selling days of those cars. Just when I thought I had one in every set, there would be a variation pop up. Cost me a lot of extra money. The up side was I could keep one and sell the newer variation which usually was a short run production or sell the whole set, which I did when I had more than one set. Great profit margin. Same with Gilbert. We all know how they produced so many uncatalogued variations with some being rarer than others thus a higher value and selling price. Like I said in the beginning, it is all about marketing and sales even 60+ years ago.New S gauge offerings from Lionel, AM and MTH are now made with multiple numbers of the same car. That is why I have so many coal hoppers, they were offered with 5 different numbers. I bought all 5 number variations in Bessemer and Lake Erie and all 5 in Erie. I have two new Santa Fe U36's because Lionel offers them in two different road numbers. I have two new Legacy Berkshires rather than one on order thanks to this. An entirely new opportunity to spend money!
Back to Gilbert, I have 27 633's. Most are different variations of painted vs unpainted, color, chassis type, truck type, reefer vs boxcar and stamping variation on the OB. Five are part of sets vs separate purchase. Plenty of totally rational reasons to have more than one Gilbert car with the same number! I see no issue with owning two 326 Hudsons, the ultimate manifestation of my favorite steam engine.
An inventory list is essential for me. My wife maintains it and I refer to it frequently. When I returned from a train show the new acquisitions had to stay on the DR table until she had the marked up inventory list. On new orders when she sees the charge on the card bill that triggers the addition to the inventory list.