This is what I got from the link;
How to get text to retain its formatting when copied to a new document
If the donor document has a style that does not exist in the recipient
document, then any text in that style copied to the recipient document will
retain its formatting.
So, to avoid text taking on the format of the styles in the recipient
document, use styles with different names.
In Word 2002 and Word 2003, you also have the option of using the Paste
Options buttons, although using them is by no means straight forward.
Then I search under Paste Options and got;
.. Match Destination Formatting
Case 1: You copied text, but not a paragrah mark.
Word completely ignores anything to do with the source style. Direct
formatting is lost.
Text takes on the style of the paragraph into which the text is inserted.
And, text takes on the direct formatting of the character that immediately
precedes where you've pasted it. Or, if it's pasted at the beginning of a
paragraph, it takes on the direct formatting of the character that follows
it.
Case 2: You copied text, including a paragraph mark.