I'm not sure I'd even call this bug, but I've noticed this in Service Desk version 8.

 

Let's say a request comes in with ID #2. and you want to Merge it with ID #1. The request gets merged but then you decide later you have to split it again. This time after you split it, it now has request ID #3.  In prior versions it would keep the same ID. Not really an issue but curious.

Eric