Here's what I have done which seems to works. I entered the full real estate taxes for the first form 8829 on line 11. On the second 8829, I entered the full amount on line 17, excess real estate taxes. It gives me the same refund number as when I entered both full amounts on line 11 and got the error. Not sure if it is the right way to do it or not, but it is the only thing working for me.
