Two F-keys simultaneously?

I'm setting up a custom touch bar setup for ProTools but one of the tools I'd like to use (the 'Smart' tool) has F6+F7 as its keyboard shortcut. BTT wont record those two simultaneously for some reason, even though MacOS does seem to allow and understand the input, even using the fn key and the touchbar F-keys.
Is there some way to bypass BTT's refusal to record the two simultaeously, or is there some workaround that will allow me to trigger a simultaneous press of both keys?