I see what you mean. Here is the exact scenario I am running into. I am using the Caption field to put runner number into through the IPTC panel. There are times in the photo when there are multiple runners in the shot and I put every number I can see (separated with a delimiter). If I have multiple photos of that pack of runners, I used to be able to copy the contents of Caption (CTRL+A then CTRL+C) in the first image, then move to the next image with that same pack of runners (ALT+]) and then paste (CTRL+V) the string of numbers (so I don't have to retype a bunch of numbers). Even if I have just a single number, the copy/paste saves me time over typing the numbers in again.
The problem comes in when the result of the paste operation adds the CR/LF *AND* I have a \{caption}\ function set later in the process. Code replacement hates the CR/LF.
If I am just printing the contents of Caption, no one will really notice the CR/LF. But code replacement is a problem.
Perhaps a test to strip any extra CR/LF in a field before the code replacement function???
-Mike