I know there were two companies involved in the construction of the transcontinental railroad, one working from Omaha toward the West and the other working from Sacramento toward the East, and I know that they met in Utah. However, when these two companies met, did they just connect the one set of railroad tracks? OR, did they have a rendezvous and then continue constructing their set of tracks to their final destinations?

TL;DR One set of tracks OR two sets of tracks that were side by side?