not all parishes have records back this far back, so it's quite possible there are other Patrick Shaughnessy baptisms that are not available either online or in the original registers. That's why knowing a location i.e. parish or town before you search is quite important.
At least you have a possible match to work on... you may be able to find clues make this baptism a little more definite, but it may never be possible to be 100% certain, unless additional evidence comes to light. e.g. following up on one or more siblings for Patrick from English/Canadian or other census returns, or as witness or godparents on baptisms of Patricks's children etc ...
might be a long shot but sometimes RC marriage record mention details about where someone was from, or where their parents live, especially if a letter of freedom was requested from the parish of baptism