Yes Jean that can be a problem. I certainly have come across entries for Gow in the civil registration index at irishgenealogy.ie which relate to Sullivan Gow. I think this again is the problem of having the digitisation done abroad without knowledgeable professional specification and monitoring of the end result.
So far looking at Donovan entries in West Cork I have come across Rossa entries that do not show up under Donovan when the surname is O Donovan Rossa.
When you are ready to share your spreadsheet or even a summary of its results I know the IGRS library would be very keen to have a copy.