How close is "sandwiched"? Like a tiny few centimeters of space between the two, or literally touching? If the cooler is touching the back silicon of the other card, you may want to consider flipping their positioning so the product with the thinner cooler will sit on top. If you want, you could always install a side fan blowing cold air in (or helping suck hot air out) if your case supports it to help with the heat.