Service animal legal requirements

[Sara Valentine]

I have a rental listed on Zillow. My terms say one small dog is allowed. I received an application from a couple that have TWO 'service dogs'. My rental has a tiny backyard and 2 dogs is too much (I am currently having to resod it because of the very large dog who is moving out). Am I required to accept renters with TWO 'service dogs' in the same family?   

Also, if I receive an application from a renter with a LARGE service dog, am I required to accept it, knowing that the grass in the small patch of lawn will not survive it (I am currently having to resod because of a departing renter's big dog).

THANKS in advance.