1 - Uncertain about something about you (I imagine technical aptitude), and want to rule out their concern 2 - There are 2 close candidates
Either way you should confirm that it is the final stage, confirm what they'd need to see to hire you and if you are feeling confident maybe use it to negotiate salary!
Sounds like you are close to getting the job though so I wouldn't dismiss it especially if you have no doubts about the company!
Needing to check the technical aptitude of someone after 5 previous interviews means your interviewing process is broken, or you're trying to convince yourself that a weak candidate is good enough. Neither option is a ringing endorsement of decision making at the company.
You can write them off based on this, but it's not pragmatic. Downside another hour of their life vs $$$ increase from the role. That 60 mins could be the difference between X00k!
> 1 - Uncertain about something about you (I imagine technical aptitude), and want to rule out their concern
They've already done live coding with you but they're not sure about your technical aptitude. So they're going to do more of the same thing that didn't work for them before. This says a lot about the company's habits.
> 2 - There are 2 close candidates
There are two close candidates. They're especially close in "live coding" ability. Let's have an async code-off! Why is live coding so important to the company? Is the other candidate going through this, too? Is the point of this really just to see which of you will swallow more BS? This also says a lot about how the company works.