Second PhD or postdoc and their effects on tenure track position
Nobody will care how many Ph.D. do you have when they consider you for a tenure track position. What will matter is number and quality of your papers/conference presentations after your PhD. If you want to change a field of your studies then it makes sense to do a second PhD. But if not, then it is a waste of time. It makes sense to delay your PhD defence rather than go for a second degree and use this time to focus on research.