Really? We have 10s of thousands (at least) of attestations to the 2020 election results, from the county clerk level on up. But nobody claimed multiple attestations are definitive in historical textual analysis, just that the criterion matters a great deal as one factor among many. Clearly, a historical event attested independently by several witnesses who didn't know one another is more likely to have actually happened than an event reported by one person. Taken together with other criteria, the criterion of multiple attestation can help historians arrive at what is likely to be true.