It is very probable that different lines of a family with a name which seems to be local to a particular area are related. Trouble is that the records only go back so far, and some of the lines will have separated before then. So we will never know. I always think it is amazing that we can go back as far as we often do, though, and that so many old records have survived. Oh, and I have a John Skillicorn in my direct line too - christened in 1819 in Lonan - so not as old as yours!