They don't have one Vmca. Which is the problem.
And TheiC has it right.
And also in our Pref Machines it is only calculated for a specific set of conditions. If you bank the aircraft more than 5 deg's it quite rapidly goes through the roof.
And V2 isn't your best angle of climb unless it satisfies another 4 conditions first. Then it maybe if your lucky.
As I said twin drivers go and find out about Vmca, once you do, you might not be as willing to do certain things close to the ground that you were happy to do before.