I am definitely in the camp of, "if your happy color is something that doesn't come along every day, items you find in that color deserve different rules." If your happy color was black (as it is for many people, and I am often one of them), you could pass on as many items in that color as you want, because there will always be another one right behind it.
Now, if your happy color is azalea pink, you need different rules for items you find in that color, because it could be a looooooong time before you meet up with another.
Which means I'm saying more or less exactly what Joy said, and Angie seconded, and others have pointed out as well. Yes, you already have a trench. No, it is not the same as this item, because that trench is a serviceable brown, whereas this one is YOUR HAPPY COLOR.
Not saying you should take the plunge, because only you can decide what you need right now. Just saying that you should evaluate the Halogen trench under different guidelines than the ones that made you buy -- and great wear from -- the brown one.
This coat would be more like a necklace. No one in the history of the world has ever "needed" a necklace, but if a necklace came along that made your heart sing, it would be worth another think. A coat in an uncommon happy color is, I think, more similar to a beautiful necklace than to your brown trench. One serves an important utilitarian function; one is only about the joy it brings.