Multiple injectors per output - probs?

[KasaRyan at aol.com]

What is the problem with running multiple injectors off of one drive channel? 
 It is a digital PWM output right?  Shouldn't both injectors either be open 
or closed at the same time?  Or do I need to use a simple transistor switch 
driven off of the ECM injector output to control the second injector.  
Hooking them in series seems to be working, and has for about 3k miles.  I am 
open to any suggestions here.
Thanks, Ryan

For those who asked - I don't have any way to look at the code in the chip or 
know what to do with it if I did.