Our home has one dishwasher.  I would like to add another dishwasher; total 2 dishwasher hooked up to the same sink.

Reading online it seems that there is a possibility for "back pressure".  Is this correct and what exactly is that?  Also, would there be a reason that I could not run both dishwashers at the same time?  Are there any other possible problems to having a second dishwasher installed?

Thanks for any guidance!