In this verse, we have two instances of the adverb straightway; in fact, these are the only occurrences of that word in the text. In the second instance, Oliver Cowdery initially omitted the straightway, but then almost immediately he supralinearly inserted it. Since the use of straightway here is optional, it is doubtful that Oliver added the second straightway in order to make the two clauses agree. More likely, 𝓞 simply had two occurrences of “and they straightway came forth”.
In both instances, Oliver Cowdery spelled the word as straitway in 𝓟. The 1830 compositor set the correct straightway but only because he consistently spelled both strait and straight as straight, no matter what the meaning. For further discussion of the spelling for strait and straight, see under 1 Nephi 8:20.
Summary: Maintain the two occurrences of straightway in Alma 14:28; Oliver Cowdery’s addition of the second occurrence most probably derives from 𝓞 itself and not from editing on his part.