Can I put a 10 pound rabbit in a hutch with a 5 pound rabbit?

Your hutch is way too small for even one rabbit. For a pair of rabbits you need no less than a 6ft long hutch attached to an 8ft long run. The hutch you have is less space than lab rabbits get!

As for pairs, being the same sex does not equal being friends. For a pair, size doesn't matter, but personalities and being spayed/neutered does. Bonding a pair is tricky and not guaranteed. And a pair needs a lot of space, at least 60 square foot, or even the most loving pair will get fed up with each other.

Rabbits need the same amount of space as you would offer a house cat.

That hutch is not enough for one rabbit, let alone two. A run is a MUST - imagine spending your life in a tiny space with no room to run and jump and stretch. Buy a run with enough room for at least two rabbits and then get a companion.

Rabbits shouldn't be kept alone as they're not animals that thrive in isolation. A good run and another small sleeping space will then be fine for 2 rabbits.

No, its way too small... That is just enough room for 1 rabbit. Get another hutch for the other rabbit so it can have it's own place to stay.