Neilo, you are exactly correct:
each image will need to have a unique ID:
<img src="images/learnbutton1.jpg" name="Image1" width="123" height="25" border="0" id="Image1" />
<img src="images/learnbutton1.jpg" name="Image2" width="123" height="25" border="0" id="Image2" />
and the onMouseOver code will need to be adjusted to usee that images unique id value:
onmouseover="MM_swapImage('Image1','','plugins/images/learnbutton2.jpg',1)"
onmouseover="MM_swapImage('Image2','','plugins/images/learnbutton2.jpg',1)"