Why is the property tax for my house listed twice?

 You correctly deducted the property tax for your home office deduction.

However, since TurboTax carried the non-business property taxes over to your Schedule A, you would not then turn around and report the same property tax on your Schedule A, unless or course you have two different property tax amounts for two different properties.

To remove the Property tax also reported on your Schedule A:

• Log into your TurboTax return
• Click on Federal Taxes
• Click on Deductions and Credits
• Under “Your tax breaks”, you will see Property (Real Estate) Taxes.  Click the Edit/Add button.
• Remove the property tax that you also reported on your Home Office Schedule
  

Thanks, this makes sense up to the "Your tax breaks" section.  I'm using TurboTax Deluxe, which has an Update button next to the 'Property Taxes' subsection of the 'Your Home' main section under 'Deductions and Credits', but when I click Update it doesn't bring me to a screen that has an Edit/Add button.  It just shows that I "reported $XXXX in property taxes on your home office" but it doesn't have any way of editing that amount.

I'm sorry - just realized you're in CD/Download.  Is the amount that applied to your home office the doubled amount?
 Try clicking on Forms in the upper right corner.  Then on the list of Forms in your return, click on Schedule A.  Click on the line that has your property tax (real estate tax - Line 6) and then click on the magnifying glass that will show just to the left of the line.  (On my return the magnifying glass was on top of the line number)  That will take you to the Tax and Interest Deduction Worksheet..  Line 2 will show you all of the amounts that make up your real estate taxes on your Schedule A.  Line 2g subtracts the amount that is applied to the home office form (8829)

Thanks!