If you want to have two versions of an experience, then the best way would be to have one in the variation and the one in the control.
In general, Qubit compares an experience (variation) against the baseline (triggers - control) instead of each other.
This is the reason the system does not allow 0-50-50, since there should be a check on the control part in order to evaluate the variations.
If you only had one variation, then it would be possible to have a 100% traffic allocated, meaning that you wouldn't need control to do any check or measure uplift
The two variations would work if you had a control part too, so that the system would compare variation1 and variation2 to the control.