It is, certainly on a PC, possible to record two USB mics simultaneously - but certainly not a good idea, because the operating system (or more likely ASIO4ALL) would have to sync one of them to the other in real time, and that's not going to give very good results. People have done it, then very quietly gone away, sold the USB mics (which are always a compromise anyway), bought a small mixer and a couple of 'normal' mics and done the job properly. The sort of mixer I'm talking about is one with a USB connection to your computer, but that allows you control and monitoring on it - in other words, outside of the PC or Mac. Even just a two-channel stereo output will enable you to keep the mics separated using the mixer's pan controls, and also you'd have far more flexibility to add other things - more mics, external feeds, whatever - as well.
Most people find that after a while, doing podcasting with just an audio interface like a Focusrite is very limiting. It has nothing to do with sound quality, but everything to do with flexibility. For more on that, there's quite a lot of useful info here: https://www.thepodcasthost.com/equipment/podcast-mixers/