[ed_denu]

The only way to safely answer your question is to know the capacities of all the components. Since you are powering 2 elements from controls that were probably designed to handle only 1, it is likely that something will fail as tr4dude pointed out.

You can determine the wattage of the elements by doing an ohms test. The controls may or may not have any markings on them indicating their capacities. The wiring also may have markings on it that will help you determine it's capacities.

Your concern about the elements getting the correct voltage isn't the issue. The voltage will remain the same, but the current draw(amperage) is what you need to be concerned about(2 elements versus 1).

Lastly, and probably most important, don't forget about the circuit you are powering your oven from. It needs to be of the proper amperage to support your load.