This is not voter fraud, but electoral fraud. You’re right about the voter fraud assessment, that voters very, very rarely commit fraud by voting twice or with another reason. It is — as you said—infinitely small.
However, electoral fraud is undeniable. We have a system with easily hackable machines, databases, and unverifiable results. It is reasonable to assume that electoral fraud has happened (Clint Curtis testified in 2004 that it did in one election), and moreover, the data for these primaries indicates it most likely did happen, and overwhelming in favor of Clinton and against Sanders. This means we need thorough, independent audits of the primaries targeted. One limited audit in Chicago already proved electoral fraud occurred during the Illinois primary and was covered up by election officials, as I mentioned in the article.
Thus, what is your evidence for it being not right or biased against Clinton?