I have found seven births in 1849 Scotland for Robert Hunter,Clackmannon,Renfrew, Lothian, are any of these places near Dumfries?
From Tinwald, County of Dumfries (Dumfries-shire)
Clackmann
an, County of Clackmannan (Clackmannanshire), is 92 miles away
Renfrew, County of Renfrew (Renfrewshire) is 77 miles away
Lothian isn't a single place. There are three counties making up Lothian: East Lothian (Haddingtonshire), Midlothian (Edinburghshire) and West Lothian (Linlithgowshire). From Tinwald to Edinburgh is 75 miles.
In the 1881 census Robert Hunter says he is 32. The census was taken on 3 April 1881, so if Robert's age is accurate he was born between 3 April 1848 and 2 April 1849 - in other words, he is three times more likely to have been born in 1848 than in 1849.
www.scotlandspeople.gov.uk lists 10 baptisms of Robert Hunters in 1849 in the Church of Scotland parish registers and two more in the Other Churches registers. Of these 12, the nearest one to Tinwald is in Ayr, County of Ayr (Ayrshire), 57 miles from Tinwald. Three of those in the OPRs have a father named Robert.
There are 13 baptisms of Robert Hunters in 1848, 10 in the OPRs, two in Other Churches and one in the RC registers. Four of those in the OPRs have a father named Robert. The nearest to Tinwald are in Glasgow, County of Lanark (Lanarkshire), 73 miles from Tinwald.
If your source, whatever it was, found only 7 in 1849, then I strongly recommend using Scotland's People in future, as your source obviously does not have all the available information.