Marriage
The first family of Julius Arnold Dugger is entirely unproven and highly speculative. His first proven marriage was in 1811 when he was already about 33 years old, so it seems likely he had been married before then.
Children
Robert T. Nave suggests that Julius A. Dugger had two sons (Mark and Meredith), though it isn't sure who their mothers would be, if they are his, they come via a marriage prior to Elizabeth Robinson (whom he married in 1811). So far, both of these are otherwise unidentified, so he could be correct in assigning them here. This was speculative on his part, and on my part as well, but I'm starting to think this is correct. Solid evidence is lacking though.
It is also possible that one other child, John A. Dugger, could belong to Julius based on the research of Dan Dugger and myself. Like the others, his parents are unproven.
Marriage
Marriage Bond in Carter Co., TN shows "Julius D. Arnold" and Elizabeth Robertson, 24 Oct 1811.