Bash tab completion shows same dir twice

[Saurabh T]

At some point during a session, tab completion starts showing the same dir 
twice. It does not happen at the start of the session. This is on Centos 8 with 
bash 4.4 (I have no way to upgrade the system). For example:

> gdb ~/x/[tab]
y/   y/

Some observations:
- When it happens, it affects the whole session (ie. all terminals and 
instances of bash) and afaik the only recourse is to log out and back in. I 
have tried and failed to figure out under what circumstances this starts to 
happen
- There is no "other" y/, it's reporting the one in ~/x/ twice.  
- It seems to be dependent on the command, eg. may happen for gdb but not for 
ls. But may not always be the same command. 

Does anyone know why this could happen and how to "reset" it? Thanks.