Short answer - no.
Each email client and person handles and "thinks" about replies differently.
For example, some people "top post", others "bottom post" or "inline reply" with the original.
Then you have others that remove the entire original post.
You also have email clients that use a '>' for the original, some that use a ':' or even a '|' - anything is possible.
You might be able to find some "rules" that would suit most but you will not suit all replies.
I guess you could run a
diff against the original, but then you have changed formatting as well as email clients that might have converted the original to HTML or from HTML to plain text. So that ain't going to work cleanly either.
One option would be to auto-insert the entire reply - as is - and then alert an Admin person that an "auto reply" had been added to the ticket system. I find a human would be able to clean up the reply very quick (if needed) or simply leave it "as is" for tracking purposes.
The convenience of the "auto reply" or "auto insert" would be enough for most people.
Hard drive space is cheap, don't sweat the little things. You would need to build some pretty complex rules that would always be changing. That would be a nightmare to maintain.