If wired in parallel, you'll get more output, but the combined impedance will be half.
If this is a system you are building, and you are putting both drivers in the same box, the Vas will double. A driver with a Qts above .5 will require a very large box. If they have a low Qts, then the optimum box will be smaller, but the lower bass output will not be as good.
If the Fs/Qes = 50 or so, a sealed box is generally better. If it's around 100, then a ported box is likely to be a better choice. If you need further help, I’m available over the phone at
https://www.6ya.com/expert/david_29ad5d1dd86564b0