Hook effect??

Has anyone ever heard of this?? 
    Supposedly after so many weeks pregnant, HCG levels are too high and they throw off the HPTs making the test line lighter or even negative. But, if you dilute your urine and take another test, the test line is much darker?! 
    Going to have to try this later! I am 6 weeks 5 days and my lines are getting lighter. Still have all of my symptoms just as bad if not worse so I  am curious as to the truth behind this!  
    Anyone tried it? What did you find??