I had the same concerns when I joined but the guys here are really helpful and set me on the right track. Ben C and Nikolaj Poulsen were a great help, I'm sure they wouldn't mind if you asked for their advice via private message.
Maybe if you have an idea about what keywords your build might be associated with you could search the site for similar builds? That would give you some idea about what you can do to make your build different.
I've never removed a build for being similar to another, not on purpose anyway...
It's bound to happen and most of the time it wasn't something the author went out of there way to do.
I have noticed that when someone is referencing other peoples builds in their discussion that they never do as well in the ranks because you're basically announcing the fact that you're just poaching ideas or playstyles from others. Name dropping doesn't win any points...
Some 'rules' are obviously un-written, starting a build by saying "This is a re-hash of The Demonhunter..." wouldn't get the post deleted but few people would bother taking it seriously and the Deathmatch would eventually eat it.
I've had one of my builds 'duplicated' in the past, same perks, race, equipment, backstory. It is a little annoying.
Someone once duplicated one of Pontys builds as well, they completely took the piss though! They even stole his characters in-game name and changed it by one letter!
I have a similar fear. I feel when I post a build, the style may be a copy or too weak to be the next-big-thing. Including by Ben, (to Ben) I fear your criticism. You seem to be a tad bit harsh, I can commend you, and hide from you. You bring a strange vibe of encouragement. I guess you could take that as a compliment.
I've had that issue a bit in the past. I start thinking "It's got this from this build, that from that..." when I get up to 4 I usually figure it's unique enough!
If you look at my Skystrider it's pretty similar to Mason's Volkihar, though how stuff is used makes it play quite differently. I wouldn't really bother yourself if you've got the same skillset as someone else; it's how you use your skills/weapons/spells/shouts that matters.
Artwork is great for inspiration, I found this little site a few months back that has absolutely tons of little images that are perfect for illustrating builds...