The second box is part of the Ultimate Oomph package, and by returning it you're effectively changing your bundle deal away from UO.
You will have to weigh up whether an alternative package (which only has one box) is cheaper for you - something which you may need to discuss with VM directly.
If the UO remains cheaper than an alternate, then you'll have to file this under "cheaper to have an extra than not", and just store the V6 in a safe place.
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