Sleepy's will deny it, but they operate stores under a variety of names. For example, Dial-a-Mattress and 1-800-mattress are the same as Sleepy's. Just different names. Better Bedding is another name.
In fact, if you want a really good deal, leave a deposit in one store, and then call the other to get a better deal. Or go online for either store and sweeten the deal.
They are very sleazy. The sales people will push the expensive merchandise to earn the bigger commission.
Go over your receipt too before you leave. If they quote you a "package price", make sure you review the itemization.