I've had this problem two years in a row and this screen is not clear.
You say
"Second, it is not unusual for taxpayers to accidentally duplicate their contributions by mistakenly entering what they perceive to be "their" contributions into the second line on the "Let's enter your HSA contributions" screen."
This should clearly state "did you contribute anything in excess of the W code on your W-2?" It just asks for the contribution amount, so I looked on my W-2 and entered that amount. Then it is telling me I have an excess contribution subject to a 6% tax, which is wrong.
Now I know how to fix it, but the dialog in this section needs to be clarified. I had the same thing happen last year and I thought "oh well, what can I do about it" and paid the 6% tax when I did not need to do so.
