They are both interchangeable, you can mix them.. now if you wish to mix in the same vial, be sure that its the same manufacture and they used the same carriers and solvent ratio..if you wish to mix in same vial, simply just boil water in smaller saucer pan, remove from heat and place vial up-right inside water and vent top to all gas discharge.. allow to sit for a bit and slowly stir now and then, this will bring the parenting hormone together, and binding both to the carrier oil..
now if you wish to mix in the same needle, you can do that as well..