If you've ever examined it, there are 4 fuse holes, 2 for each tube. The middle pair are very close together - presumeably so that the ignition would be simultainous. The variability though is in the two different times for the ignition to travel down to each powder charge.
Firing both electronically would undoubtedly remove ONE variable, and reduce the difference in starting times.
SOMEWHERE there is a thread here where I posted closeup pix a number of years ago.