St Barnabas was built 1832 - any record before this date is junk - see www.manxnotebook.com/parishes/do/douglas.htm#StBarnabas

my reading of IGI is
PHILIP DSG 18190131
MARY ANN DSG 18210304
JANE DSG 18230713
ELIZABETH DSG 18250904
SARAH ELLEN DSG 18271216
JOHN JOSEPH DSM 18331005
JOHN JOSEPH DSB 18360527
SARAH DSB 18360527
ELIZABETH DSB 18400109
DSG = Douglas St George's, DSM Douglas St Mathew's, DSB = douglas St Barnabas
I have seen a few cases of double baptisms around this period usualy when a sibling is baptised - I havn't checked whether this is a misreading of the actual entry or an actual record - st Barnabas has the more charismatic vicar at this time