Some version of Vegas introduced event snapping, in which blue vertical lines would show up when you had events on different tracks aligned. I don't recall if this was 8 or 9. Look under options and see if there's something like that you can enable.

Lacking that, i put the cursor at the beginning of that chunk on the source track before i do the paste. Then after pasting you can drag the copy to the cursor and it will snap into position on the destination track.