There can certainly be parallel etymologies or simultaneously being two forms. Like I said, I heard “Holmes” in the 80s, and I’ve provided a written cite for “holmes” as early as the late 70s. To me, it looks like the “homes” form was probably the earlier one, and then sometime in the 70s, the “holmes” variation cropped up. When I hear “holmes,” I think of Latino subculture. “Homes,” African-American subculture.
As suburban white kids calling each other “Holmes” in the 90s, my friends and I debated the origins. We decided that it must somehow be related to John Holmes, but Google is devoid of any evidence of that. Circumstantially, he may have been a household name around the time the term caught on (early 70s).
Back in the eighties a buddy said to me “hey hommes”. I said WTF did you just call me and he said “hommes, its French for Man.”
This story should really burnish my “White and Nerdy” cred. 
The first time I encountered this particular slang was in college, and one guy in our social group (he was from Chicago, if I remember right), tended to call us “homes.” At the time, being completely unfamiliar with the term, I heard it as “Holmes.” So I started responding by calling him “Watson,” all the while wondering why we had suddenly adopted this weird Sherlock Holmes role-playing thing. Eventually he explained what he was really saying. This would have been in the late 1980s.
So I can completely believe the theory that it started as “homes,” and morphed into “Holmes” among some people, either through mis-hearing or as a deliberate joke. Because that’s exactly what happened to me.
This seems the most likely scenario to me. The only real cultural connection to “Holmes” is Sherlock, and that seems highly unlikely for a black/Latino gang-related phrase from the 1970s. If anything it’s just a lexical shift. We see these all the time, especially with slang phrases that start out unwritten, and then shift when people start writing them down.
I have a two-part theory for how this shift from “homes” to “holmes” may have occurred.
Since “homes” is not related to any common English name, I can easily see someone (especially from outside the communities of origin) hearing it, and then parsing it as “Holmes.”
I think accent may play a role too. Some so-Cal Latino folks, have a different “o” sound in “homes” than say, a white midwesterner, or east coast dweller. To my ear it’s more like a round-mouthed “ohh” than a purse-lipped “owe.” I can see that “ohh” sound being mistaken for the vowel sound in “Holmes” as opposed to “homes.”
Of course no one thinks about these things, but one person does it, maybe somewhere influential, and since “homes” was not originally something that was written down, the variant sticks. Eventually even people using it in the communities of origin may think of it as “holmes” or even start to pronounce the silent “l” a bit.
Title edited to better indicate subject.
Colibri
General Questions Moderator
Growing up in Los Angeles I would have said that, back in the 80s, ‘Homey’ or ‘Homeboy’ was something I heard the African-American kids in high school us.
‘Holmes’, on the other hand, was more of a Latino thing. It was definitely out there on the street by 1985 in SoCal.
To my ear, hombre can sometimes have an added L like almbre.
I’m a little bit confused by this thread in that I, and I’m pretty sure Will Smith, would pronounce “homes” and “Holmes“ identically, the latter having no /l/ sound in it.
I was in LA before you (early 80’s) and it was in use around that time too. Not linked to any particular ethnic group, it was used by black, white and Hispanic kids I knew.
Wiktionary:
I know “Hey, Holmes!” was in use in my area in 1989. My high school yearbook is my cite. 
Judging from who wrote it, and how I was in high school, I’m thinking we picked it up from Cheech and Chong.
http://www.subzin.com/quotes/M8245c03f/Cheech+and+Chong's+Next+Movie/Hey%2C+Holmes.
Los Angeles, early 1970s, hispanic jr. high, it was holmes.
For most Americans, there’s no difference in the pronunciation of “homes” and “Holmes”. I’m surprised that so many people are so sure they heard one and not the other.
Yeah, looking back at this thread years later, I see what you’re saying. But I am one of the Americans who do say the “l” there, as well as the “l” in “folk” and “yolk.” Might just be a quirk of my pronunciation, though, as I do know those words often don’t have the “l” pronounced.
I always thought “homes” as a derivative of “homeboy.” A homeboy was someone that you knew from your neighborhood, or your “home” and was someone you could trust. Saying “Hey homes” was the urban equivalent of saying “Hey, pal” or “Hey, buddy” or “Hey, friend”
Holmes doesn’t make much sense.
Duplicate.
On this, I agree with you.
From the 90s to not too long I ago I recall hearing ( phonetically ) Wha-SAH! for Wass-up ( What’s up ). I’d also hear it shortened a lot to just Sah! ( phonetically )