Per this NWC forum thread: Opening NWC BAK files, from NWC 2.1 there is an Open Backup option on the file menu. Before that you need to rename them to .nwc


The following from the (2.1) manual shows why multiple versions of backup files may be created:

Backup Files

You have the option of creating a backup file (*.bak) of your *.nwc song file when you save the *.nwc file.
The backup file could be used if the original *.nwc file became corrupted or lost. To have backup files created, in Tools: Options, File, check Backup files during save The location where backup files will be saved is set with Tools: Options, Folders, Backup Files.
Multiple backup files can be created as you work, in case you need to go back to an earlier saved version. To the right of Backup files during save, select a number for Queue size for extra backups The back up files will be named filename.nwc.bak, filename.q1.nwc.bak, filename.q2.nwc.bak, etc.

The naming convention here doesn't seem to fit the names of your files. What version are you using? (I don't use NWC, this was just from web search)


Mick