Hi @maxwellh ,
You have to be careful how you connect them.
If you connect them in a parallel configuration to the amp output, you will reduce the resistance (halve) that the amp sees and the current will increase (double - Ohm's law). Hopefully your amp can handle the increased current and not overload or blow.
If you connect them in series configuration to the amp output, you increase (double) the resistance but will not endanger the amp.
You will have to view the ratings of the amp to decide which is the better option
Here is a link that probably explains it better than I can