What is the significance of Aunt Clara and Clara the brothel owner having the same name in Of Mice and Men?

During the Great Depression, the traditional family structure often fell apart as farms failed and jobs grew scarce. Fathers left to find work and young single men hesitated to enter serious relationships, given the financial responsibilities attached thereto. These men often traveled and worked solely in the company of other men in a world devoid of mothers and wives. Aunt Clara and the Clara of the brothel represent surrogates, or stand-ins, for those respective roles.

We first encounter the non-traditional family setting when Lenny refers to his Aunt Clara, who "used to give [mice] to me.... I'd pet 'em." When Lennie threatens to run away, George reminds him, "Your Aunt Clara wouldn't like you running off by yourself, even if she is dead." This is obviously a woman who has loved and nurtured Lennie. Later, at the ranch, George tells Slim, "I knowed his Aunt Clara. She took him when he was a baby and raised him up." The timing would have preceded the Great Depression, but this detail introduces the idea of a surrogate mother. 

Similarly, prostitutes substituted for wives among the itinerant workers. They offered physical comfort with no familial strings, as George says:

You give me a good whore house every time.... A guy can go in an' get drunk and get ever'thing outta his system all at once, an' no messes.

Clara's place is one of two local brothels; hers is the less desirable of the two. Susy, the rival madam, insists, "My girls is clean...an' there ain't no water in the whiskey." The fact that Clara stays in business emphasizes the idea that men would seek the company of nameless, faceless women even in the seediest of places.