The more important question is will Canon's software allow that/work?
A Canon forum will probably be a better resource. And I'd test outside of OBS (ie OBS not even running). I'm a Canon 80D shooter, but Canon's s/w leaves a LOT to be desired. So assuming the software can handle 2 cameras, or will be stable if running 2 instances? not something to assume
Then, if the Canon USB webcam s/w does work with 2 cameras at same time, then you may run into an issue with device name. See threads of Logitech webcams especially with same device name causing issues (problem isn't OBS, but poor device (mfg) drivers).
Good luck
An alternative, that would be more complex, but much higher resolution due Canon 90D only being able to transfer at USB2.0 speeds (from what I read online, a Canon hardware limitation in camera), would be to use a Clean HDMI out instead, and a USB3 HDMI capture card. You'll get MUCH better image quality this way (vs the USB route)