I have a small fridge-freezer because that's all I have space for in my small kitchen. But it's never big enough. I would love another in my utility room where there is plenty of space. This could not be the main place for the fridge because it's not in the kitchen. I have enough cash to buy the 2nd fridge. But fridges contribute towards greenhouse gases - would it be ethically right to have two?
If you need two, and have the space for two, then get two. Only you can decide how "green" it is and if it's justified. There are so many things we do in our lives that aren't strictly necessary, and we could do without, but it's for every individual to decide where they draw their own personal line between comfort / convenience and 'worrying about the future planet'.