After the Nephites had sufficiently prevailed in battle to force the Amlicites into flight. Alma has his army pursue them.
This pursuit was necessary to make sure that the Amlicites were sufficiently driven from Nephite lands that they did not quickly regroup and attack again. In the valley of Gideon he calls off the pursuit, but he is not yet satisfied that they are out of danger.
There is still the possibility that the Amlicites might regroup. To obtain intelligence as to the disposition of the remainder of the Amlicite army, Alma sends out spies to watch what becomes of the Amlicites.
Textual: Mormon gives us the names of the four men who are sent to be spies. This is the only time that their names appear in the Book of Mormon (as personal names). These men have no other historical role that we have recorded in our text.
Why did Mormon choose to name them? Of course we cannot know. It is obvious that their names were duly recorded in Mormon's source material. Perhaps Mormon's military sensibilities required him to make sure that credit was given where credit was due.
Two of the names do appear again in the Book of Mormon, but not as personal names. Manti is a hill, and a land. Amnor is apparently a measurement:
Alma 11:6 A senum of silver, an amnor of silver, an ezrom of silver, and an onti of silver.
7 A senum of silver was equal to a senine of gold, and either for a measure of barley, and also for a measure of every kind of grain.
8 Now the amount of a seon of gold was twice the value of a senine.
9 And a shum of gold was twice the value of a seon.
10 And a limnah of gold was the value of them all.
11 And an amnor of silver was as great as two senums.
We can only speculate on the relationship between the personal name and the measurement.
Since the measure appears to be tied to the thing measured (an amnor of silver apparently corresponding to a seon of gold), it is possible that the name was more than a measure, but a measure of something of value. This latter meaning might reasonably be used as a personal name.