One owner along the half mile of hoppin’ shops along trendy Washington Avenue was puzzled late Friday night to find a street vendor setting up his cart on the sidewalk patio outside of his front door. The store owner, who pays the city a fee for the use of the public space, found that the street vendor had been issued a permit by the Streets Dept. for the identical space.  After a visit by the police, the dueling eateries cohabited for the evening, but vowed to sort out the matter with their aldermen and other city officials this week.