With a simple cut and paste, rather than copying exactly as in the orignal source, FrontPage will convert HTML symbols such as the brackets < > to weird symbols: < >
FrontPage thinks you're pasting ordinary text that happens to contain a lot of angle brackets. Therefore, it converts < and > marks to < and > so the browser displays the angle brackets as text rather than "mistakenly" interpreting them as HTML.
To avoid this problem, either paste the HTML into HTML view (which may have the same effect anyway), or choose Paste Special from the Edit menu. After choosing Paste Special, choose Treat As HTML.
Alternatively, open a new Notepad document, and paste into that, then cut and paste from Notepad into FrontPage HTML view. Using Notepad as a go-between assures any HTML elements are retained correctly.