Education use

Working on integrating the program into speech therapy sessions. Can I recore 2 lines. 1 being my voice giving stimulus words and one line where the client repeats those words trying to match the formant pattern for correct speech sound production.

The simple answer is yes, but the devil is in the details. Since it is very rare to have two microphone inputs built into a computer you will probably need some hardware to accomplish this. Given that a decent XLR->USB adapter (plug any XLR microphone into any USB port on your computer) costs about $100 each (and I’m not sure how easy it would be with Audacity to record two such adapters at the same time), and an equally decent multi-channel USB mixer is about $200, I suspect that the mixer would be your easiest and best choice. You would plug two microphones in the mixer and then record stereo from the mixer with each microphone on its own dedicated channel of the stereo track (left/right).

Two XLR microphones plugged into a stereo (2 channel) “USB microphone pre-amp” could do the job.
A low budget example:
ART USB Dual Pre
ART USB Dual Pre