you can but it will put more strain on your pump so it wont last as long
Gotta say i dont agree, had one pump on 2 reels not even with a varistream, just a tap back to tank. For a year and half, its fine...might even be longer actualy thinking about it, and i bought it second hand, it must be about 3 years old.
As said, up the pressure a little. If one finishes a bit earlier than other you get more pressure in the one...but its not really an issue to be fair, especially if your working well together.