Using conflicting gimmicks and names isn't always a death blow. In fact, it can actually create really cool relationships. Obviously never intentionally name your team the LightningRoosters so that you can befriend the Thunderchickens, but it's not the end of the world if you share a gimmick. For example, 1714 and 1086 both have blue uniforms and cheeseheads. We learned of this at Atlanta on 2008... "Why does a team from Virginia wear cheese????". We then picked 1086 as alliance partners and enjoy talking to them every time we go to Atlanta. Perhaps someday a Cheese Head Alliance will win the Newton Division?
Anyway, if you're really concerned, you can ask here on Chief Delphi if a gimmick's been done by a "big name team" or whatnot.