The original text has many examples of the auxiliary verb do immediately followed by the main verb, as in this example of “did travel” in 1 Nephi 2:5. There are two other examples in 1 Nephi 2 involving the use of the auxiliary do, although one is not original to the text:
A few of these auxiliary do’s have been removed from the text, as in the example from 1 Nephi 2:14. And in some cases, the auxiliary do has been accidentally added, as in the example from 1 Nephi 2:16. For a complete listing, see do auxiliary in volume 3.
In the example from 1 Nephi 2:5, Oliver Cowdery later corrected the original manuscript’s “he did travel” by adding (with somewhat heavier ink flow) a past-tense d to the end of the verb travel. However, he did not cross out the auxiliary verb do. And when he copied this verb phrase into the printer’s manuscript, he retained the original “did travel”. His partial alteration may have been an attempt at editing the text. Perhaps he was trying to make the verb agree with the traveled of the preceding sentence (“and he traveled in the wilderness in the borders which was nearer the Red Sea”).
The King James Bible has numerous examples of the do auxiliary occurring in positive declarative clauses. In the following passage, all the verbs take the simple past-tense form except for one, which has the archaic did wipe instead of wiped:
Although such examples of the auxiliary verb do are common in Middle English and Early Modern English, such usage is unacceptable in today’s English—unless there is stress or emphasis on the do auxiliary (which is definitely not the case in the examples from the Book of Mormon).
Summary: Follow the earliest textual sources in either restoring or removing the auxiliary verb do; here in 1 Nephi 2:5, Oliver Cowdery originally wrote did travel; his later attempt to emend it to traveled appears to be secondary and should therefore be ignored.