Based on what dj said, there is absolutely no possible way that there could be any possible evidence of the kind of abuse you mention.
Two submittals of a legitimate site won't be considered spam. There are simply too many plausible ways for legitimate submittals to end up doubled. And it has to be pretty severe spam, or pretty deliberately deceptive spam, to cause a site to be rejected altogether.
Actually, in fact, there are some principles that I've found almost always applicable: (1) people who are concerned about spamming, just don't; while spammers are nearly always blithely unconcerned about their deeds, and often blame their own rudeness on us! (2) The vast majority of sites that are aggressively submitted aren't worth listing at all. There are tens of thousands of jerks out there who will tell you, "I submitted my site more than once and now it's not listed--that second submittal doomed me" -- while the truth is that they had submitted their worthless site more than a dozen times, and still it was the site's worthlessness rather than their jerkishness that caused the rejection. (3) Very few sites are reviewed by competitors. The vast majority of sites are reviewed by very-active editors (well, duh!, you say, but hear me out) who CAN'T POSSIBLY have been competitors of more than a fraction of a percent of the sites they reviewed.
