A name change from BORG to BORGQUIST

In May 2009 I published two posts regarding sons of Pehr Hansson Borg and thier name change. In my research I haven't found a reason why this happened however the date of the change is in the 1860's. Svenn Pehrsson and Rasmus Pehrsson changed thier surname from BORG to BORGQUIST. Both of the young men are posted on the ship roster as BORG, however records in Utah show the surname of BORGQUIST.