X1 Yoga Dual Boot

Hello all,

So I have a Lenovo X1 Yoga that I installed Mac OS 10.14.6 onto. Now I have a 512GB SSD that I have Windows on, and a 256 SSD that I had Mac OS on. I wanted to combine them onto one 1TB SSD. How should I copy everything over? Do I need to reinstall Mac OS? I did a clean vanilla install.

Thanks,

Jason