complete with errors

I have Acronis True Image Home 2009. Recently I set it up for a backup and went away for a few hours. When I returned, it had actually done three backups. The log reported that the first two were "complete with errors" and the last was completed satisfactorily.

What happened? It appears that Acronis completes a backup with error, then fixes the error and tries again until it completes satisfactorily. I don't see how it could fix some file error. Can I throw the two backups with error away and keep the satisfactory one?

Can someone explain what is going on?

Thank you.

Stu