There's no way to predict accurately how a combination of drugs will affect any individual.
Drug interactions are complex.
Taking two different stimulants is likely to have a different effect from taking twice the amount of one drug. The best advice is not to mix any drugs - and that includes alcohol or prescription drugs. If you do take more than one drug a night, the most important thing is to remember what you have taken, when, and to allow time for the effects to kick in and wear off. Not only is this much safer, but it also means you're more likely to get the effect intended. However the combination of these two drugs may have a contradictory effect making you feel edgy and paranoid instead of calm.