Strange Behavior in Extention Manager

Using Ext Manager 13.0.135

This might be a bug or it might be by design.   

In our environment we have three Exts that are allowed more than one endpoint.   For example 1100 shows in EM Manager as 1100-1 User Name:  

I select 1100-1 User Name and then program the extention as normal.  

EM will create the XML files as it should naming them 1100-1.xml and 1100-1-blf.xml

However when it creates the CFG file it doesn't use these names,   It uses 1100, so when it reconfigs the phone the CFG files are looking for files that don't exist.   

If I go into the CFG and edit the CFG to use the correct file names everything works as expected.   

The problem is the next change I make in the EM will update the XML files as expected but will also update the CFG file back to the wrong XML File names. 

Has anyone else experienced this?