New Rule when entering reviews


I have noticed allot of people that are entering my review already have their own review site. The last few winners I have chosen all had sites that they have reviewed some or all of the same products I have.  
To me that's not fair to the companies that send out products to review. 
If you have your own site or you have already won the same item that I am reviewing from another site PLEASE don't enter my reviews. 

As much as I like to have new entries I just don't find it fair. 

Thank you!