If you don't, the two documents will be joined together. File not found. The original file remains unchanged on the disk unless you replace it when you save the file on your screen. Every time you decide on the format of a document, such as line spacing or centering, a code is inserted for that decision. WordPerfect uses these codes as instructions to display your document correctly on the screen and later to print the document the way you want it.
Every special instruction has a code.
Normally, you don't see the codes, but they are always there. The codes don't appear unless you decide to look at them. WordPerfect splits the screen with a tab ruler line. The top section shows the text you typed and the bottom shows the same lines with the codes. You can delete the codes.