Regardless of one or two, voltage accuracy depends on the calibration. Splitting has no measurable impact on accuracy, even splitting 4 or 5 times. With a splitter, you should expect identical voltage readings in the two units so long as you use the same calibration value.
Practical considerations should govern here. If the two units will be colocated, the splitter makes a lot of sense. If they are far apart, it may be more convenient to use a separate VT.