"You already have an active portfolio export in this session. Before continuing, you must either complete this export, or cancel it. Would you like to continue it? (No will cancel it)
YES NO"
Should be:
"You already have an active portfolio export in this session. Before continuing, you must either complete this export, or cancel it."
COMPLETE CANCEL
I'm pretty sure one of the yesno functions allows custom button names
Cheers!