From reading your post, plus the reply from ciderdrinker and then looking at the records myself, we do indeed have 2 Henry's, one son of Edward bp'd 9/9/1792 and the other who would appear to be the son of Edward's brother Richard.
However, you state that 'your' Henry who married Bridget was the one born 1792, son of Edward but I don't think this is so - although shown as bc.1796 in 1841, in 1851 census Henry (married to Bridget) is shown as bc.1789 and his death in 1858 shows him as 70 i.e. bc.1788.
I think ciderdrinker is correct in that Edward's brother Richard married Sarah Wall 1786 and that this couple had children baptised Darley i.e. Samuel 1786, Edward 1793, Sarah 1795, Mary Ann 1798 and Alice 1800 and that there is a gap 1787-1792. I, too, think that the Henry Milner bp.19/10/1788 Allestree, son of Richard and Sarah, is a son of this couple plus there was also a daughter Elizabeth bp.19/6/1791 Allestree so would appear that Richard and Sarah left Darley for Allestree between 1787-1791 and had returned to Darley by 1793 when son Edward born.
There are trees on Ancestry stating that the Henry Milner bp.9/9/1792, son of Edward, is the Henry Milner who married Mary Seales and I would tend to agree with them. His ca.birthdate of 1793 is consistent on census and age at death.
'Your' Henry married Bridget and in 1841 census both are shown as bc.1796 - however, in 1851 Henry shown bc.1789 and death in 1858 is at age 70 (bc.1788).
I firmly believe that 'your' Henry is the one baptised 19/10/1788 Allestree, son of Richard and Sarah, and not the Henry baptised 1792 Darley (son of Richard's brother Edward) who married Mary and whose age on the various census, and age at death, is consistent with this birthdate whereas 'your' Henry was actually bc.1788/9. Although shown as born in Darley he was probably unaware that his parents had briefly lived in Allestree between 1787 and 1791 where he and a sister Elizabeth were baptised before family returned to Darley by 1792.
Annette