Lines 26 and 27 of IRS Form 4562 Depreciation and Amortization are for listed assets. Rental real property is not listed property.
Property placed in service in the current tax year will appear on Line 19 and any older properties will appear on Line 17. When entering the depreciation information for a rental duplex, of which you inhabit half of the property, you would multiply the cost basis by the rental percentage and enter that as the basis of the asset. You would then keep the business percentage as 100%.
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.