1999 was the only year Utah played Boise in Boise. While they did have a blue turf at the time, and they did have blue uniforms that they could wear, I cant find any evidence that they were blue on blue for that game and there was a pretty clear difference between the two colors anyway. They've sorta leaned into it a little more recently where the turf and the uniform match up really well color wise.
Pic of boise in 99 wearing all blue on their turf as an example:
http://digital.boisestate.edu/cdm/singleitem/collection/archives/id/2542/rec/2407