As long as you have good case airflow and the cards are not stacked on top of one another. Most boards leave at least 1 or 2 slots clearance between the space required for (2) 2 slot video cards. However, some boards do not and they are stacked right up against one another. Those tend to have issues. I had that issue in the past myself.
Just monitor temps, especially on the top card as the heat from the bottom card with raise and increase it's temp. Does your case allow for a side fan that you can install to circulate air between the cards? That is where the hot spot sits. Also, consider whether they are blower fans that send hot air out of the case or if they circulate the hot air withing the case. Sometimes SLI setups work well with blower style fans, especially if you have limited space in a case and airflow.