Hello CH! I'm interested to participate in your contest. It would be nice if you can #sealed the contest. Some of the designers feel confident to participate in contests that offer to protect them work by sealing it (so only you can see it). Also, it is a plus cuz nobody copies other designer’s work.
Also you can use this following links to have an idea of what is a generic prefab logo: (beware! Because you might get something similar to these as well, happens almost every time)
Now you can be sure which designer is giving you a design completely made by itself and you can feedback and rating to guide them get better. Some of the designers feel more confidence to participate in contests that offer to protect them work by sealing it and by guaranteeing the final price.