Does proximity of same stores matter?

[azxcvbnm321]

How much will proximity to another store selling the same item affect demand? In a lot of cases I'm forced to open a store right next to an AI store because of location. And later on, some stores like convenience stores, run out of suitable locations so I have to build them fairly close to another one of my convenience stores that sell the same item. It is not always possible to build a discount megastore or supermarket either and I won't get the chain store demand bonus. Any ideas?