Just a word of warning about the Maxtor. I have one and found that some of my backup photos were corrupted on it. Fortunately I had another set on a DVD. Have you verified that the data is OK?
I like to have data on a dvd as an extra back up.
Back to your original question - I cannot see a major problem unless the Maxtor Backup software becomes confused to which drive is which.
As well as my Maxtor I have a WD external hard drive which Acronis backs up to.