I'm pretty certain they are both from the same person, Harry Perry, which is why they are so close in text but several years apart. As you say Sharp wrote it down from him on the way back from America aboard the St Paul, and we don't know for certain when Colcord noted it down from him but it could have been something like 10 years later, plenty of time to remember another verse and forget an old one. If I am right the differences in tune would make a fascinating study, apart from the textual differences. Also we don't know to what extent Sharp and Colcord were merely taking an impression of the tune. A musicologist might be able to explain why Sharp's in most places is about a tone above what Colcord noted.