Daniel was pretty close to Alexander on the 1840 census in Roane Co., TN. Alexander did have an unidentified son around his age on the 1830 census.
Daniel R. Dugger was listed on the 1840 census in Roane Co., TN two houses from Alexander Dugger, his probable father. His name was spelled oddly. They were pretty close to Hezekiah Love, probably a close relative of Daniel's wife.
* Roane Co., TN page 54 Danel R. Douger 0000100000000-0001000000000
* Analysis:
* 1 male 20-29 (1810/1820)=Daniel R. Dugger (1810/20)
* 1 female 15-19 (1820/1825)=Elizabeth Love wife
I couldn't find them on the 1850 census.