Prerna,
I can see two issues here.
1. Data issue in SAP. Table with ILNNR filed is having data + non-printable character. May be SAP GUI when user press enter after filling some data is storing that 'Enter' value. Request SAP ECC team to fix data issues / user interface program.
2. Keyboard 'Enter' is getting converted to 
 . Ideally it should be converted to OR U+000D. http://unicode-table.com/en/#000D
If it is not possible to handle these issues in SAP ECC. You can handle in message mapping (not recommended), using standard function replaceString.
