> A lot of times I find that they are and have already been verified, but the other operator must have re-sent them with some thing changed, like time or something. Don't know why they do this.
My guess is that's an artifact of their logging program. They may have it set to "upload automatically all new QSOs." They might then update the QSO if they either find a spelling error ("Rick" instead of "Dick", or in the QTH, or something), and then the logger views this as a new QSO.
I doubt if the operator is doing it intentionally.