When you shoot with an illuminated rear background (like a softbox firing light toward the lens), firing a second light onto the subject usually gives an exposure that looks "right" without the need for much post-processing adjustment, or dodging of shadows.
Little tip on Speedotron Brown Line. Look at the three-light power output options in Asymmetrical output mode: One light firing at 200 Watt-seconds in either outlet 1 or 2; and two lights putting out 50 Watt-seconds in outlets 3 and 4. So, outputs of 200/50/50 Watt-seconds.
Or, the alternate choice, two lights each at 140 Watt-seconds in outlets 1 and 2, and the third light in outlet 3 or 4, giving off 70 Watt-seconds. So, outputs of 140/140/70 Watt-seconds.
You can put the "strong lights" of 140 and 140 on a 9-foot wide roll of gray paper aimed in at 45 degrees, and key shift that gray paper right on up to pure,glorious white background if you light the subject with the 70 Watt-second light at a normal, classical distance.
The 200 Watt-second option from one light and then two lights, each at 50 Watt-seconds gives a main and an accent light or main + hair light option that is very handy.
Brown Line 402 packs are what I use most of the time; the ratios in Asymmetrical have been carefully thought out for real-world conditions using white, gray, or black backdrops.