you should just keep going. In the art world this happens all the time, and it took me a while to realize that it doesn't matter if someone has done "the same thing" before, as every person will do it differently. Making is a process of choices, and no two people will make the same choices, so the end result will always be different. As well as that, your choices will be tempered by what you know about the other "same project", and you'll probably make it differently in five or ten ways.
D