Robert Martin and Jane Patterson

My Great Great Great Great Grandfather Robert Martin is married to a Jane Patterson in many family pedigrees shared on Ancestry.com.  I have found a child Robert Martin, christened  7 July 1796 in Dromore Parish. My Great Great Great Grandfather is also Robert Martin. I have found another child John Martin, christened 23 Jan 1839, also in Dromore Parish. These two christening records were found in Ireland Births and Baptisms, 1620 - 1881 on familysearch.org.  I have several questions about this family. There is a 43 year span between these births, is it possible there were more children born inbetween and the records aren't available, or at least not online, or is it more likely they are children of two different couples?  When I use a parish locator, I find that It is 58.1 Miles (93.6 Kms); East by South East (104 Degrees). FROM:- Dromore, C, TYR,IRL. TO:- Drumgooland Upr, C, DOW, IRL.  Is it feasible this Robert is the correct Robert?  I'm wondering why Jane Patterson has been added to this line, do you know where there would be a source to verify this?  Great Great Great Grandfather Robert Martin married Jane Nicholsen and theeir children were all born in Legananny according to my Great Grandfather.  Can you give me any guidance on how to research this more?  I have sources for most of the children, so we're only concentrating on Robert Martin and Jane Patterson, and their children.  Any help would be greatly appreciated.  Thanks for your time!