Shrivallabha (MrExcel user name Taurean) posted a link to this thread in July. Yes it looks like a bug.
How to remove duplicate from a integer,integer+txt values « Chandoo.org - Learn Excel & Charting Online - Forums
Looks like Chandoo.org reorganized their site which changed the location of that thread.
Here is a link that works as of today.
How to remove duplicate from a integer,integer+txt values | Chandoo.org Excel Forums - Become Awesome in Excel