James Clark (1782-1865) died in Paisley Abbey district, mother's maiden surname Campbell. His death certificate says that he was the widower of Agnes McFarlane, and his parents were James Clark and Margaret Campbell. 
James Clark 1782-1865 and Agnes McFarlane were married in Paisley in 1830, and they did indeed have a son Robert; he was baptised in Paisley on 24 March 1833. He would have been just 7 years old when your Robert Clark married Ann Phil*p* in 1830. 
According to a newspaper article in 1878, "The members and sole partners of the firm of Clark and Co are James, John, Stewart and William Clark. The family has been connected .... with the manufacture of sewing cotton since its introduction at the beginning of this century, and .... as far back as 1720 were engaged in the manufacture of linen thread ....".
Stewart Clark died on 20 November 1907 aged 77. According to the deaths index his mother's maiden name was Aitken. John Clark, mother's maiden name Aitken, died at Gateside, Paisley in 1894 aged 66. Newspaper obituaries confirm that these were the John and Stewart Clark of the thread manufacturing company. 
John Clark and Elisabeth Aitken were married in Paisley in 1819. Inconveniently, the threadmill Clarks seem to have belonged to one of the dissenting churches, and there are just two baptisms of their children readily available: Elisabeth in 1820 and James in 1821. However there is a Clark family  at Gateside, Paisley, in the 1841 census consisting of John, 45; Eliza; 40; Elisabeth, 20; James, 19; Margaret, 15; John, 14; Stewart, 11; Anna, 8; Jane, 6; Robert, 5; Alexander, 3; and William, 3 months. 
In 1851, at Gateside, Paisley, are John Clark, 58, thread manufacturer, born Paisley; wife Elizabeth, 55; children George, 27; John, 23; Stewart, 21; Annabella, 19; Jane, 17; Robert R, 15; Alexander, 13.
From this I deduce that the four thread mill Clark brothers were the family of John, not James, Clark. 
Turning to Aberdeenshire, James Clark and Janet Morice had at least five of a family: Margaret, 1801; James, 1803; Andrew, 1808; Robert, 1810; Helen, 1813. This means that their father James must have been born before 1786, as a boy could not legally marry until he was 14. The chances are that he was a good ten years older than that, born around 1770. 
Andrew Clark, born Crathy, agricultural labourer, was in Rescobie, Angus in 1851 with a wife and family, and Andrew Clark, 57, mother's surname Morris, died in Murroes, Angus, in 1865. His death certificate confirms that his parents were James Clark, labourer, and Janet Morris, and his death was registered by his brother Robert. 
So none of the detail fits. 
I also think it's rather unlikely that James Clark, son of a thread manufacturer in Paisley, would move to the remotest corner of Aberdeenshire, marry there before he was 18, earn a living as a labourer for a few years, return to the fold in Paisley by 1830, marry again there and start a new family.