Dina, my experience has been that Gedmatch is pretty close on MRCA estimates. When I have a 4.4, it's usually 5. Depends on the size of the segment. Are you sharing a common segment with both descendants, or are you sharing one segment with one descendant and one with the other? Also, what is the size of the segment?
I found your question more interesting than average, as I have a Maurer brick wall in my ancestry. I never thought about a possible spelling of Mowery. The ones I've located thus far are Mower, Mowder, Mouder, Maurer, Mourer, Moder, Mauerer, Mauder. Mine were in Pennsylvania and supposedly from Scotland . . .