Image Files Naming Issue (?)

I am using Acronis® True Image Echo Workstation® with Acronis Universal Restore® (build 8,398). I have noticed this over the past few weeks of imaging and do not know if this will be a problem to try and restore an image. In order to save space on the backup drive where the images are written, I have the software over write the previous image. Here is the sequence:

Base image name: BACKUP.tib
First Incremental: BACKUP1.tIB
Second Incremental: BACKUP2.tib
Third Incremental: BACKUP3.tib

Here is where the change comes into play. The next weeks series of images, I end up with these file names:

Base Image: BACKUP1.tib (Notice here how a number 1 was appended to the file)
First Incremental: BACKUP2.tib
Second Incremental: BACKUP3.tib
Third Incremental: BACKUP4.tib

When the second set of incremental is attempted this is the error I receive (I suspect because of the appended "1" now):

"C0064006C: Incremental backup is not possible.

The file you have chosen is not the Acronis True Image backup, or the file is corrupted, or this is not the last volume of multi-volume archive.
Do you wish to proceed with the current file name? If you proceed, the chosen file will be overwritten and the full backup will be created.
Otherwise, you will create an incremental backup by choosing the valid archive file name or the last volume of multi-volume archive"

So how do I correct this problem?

Thank you for your input and suggestions.