For a pair it's best to have a cage of around 80x50cm - I've heard that Detolfs are great for pairs as it can be divided if they fight.
Chances of them fighting are quite high, especially if they are from a pet shop where litters are mixed. They would need to be scatter-fed, you'd need two of everything and you'd need to be on the watch pretty much 24/7 to check for fighting.
You need to ask yourself: Can I take the precautions to avoid fighting? Do I have the money for another cage? Do I have the space for another cage? Will I be able to cover the vet bills if one is seriously injured? What would you do if one killed the other? These are all very important points that must be considered.
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Minion to Daisy, Lily, Harry and Peanut <3
Gone but never forgotten
Willow - 18:27 18th November 2016