just cant understand it why why why

[Byron]

Remember also that the internet is so full that links are getting longer and longer and so it takes little to cause confusion and so a disruption.

You are right to say that site IDs will often appear twice and you should follow the lower one - important to remember however that what you read may not be ALL of it - there is simply not enough room in the box (pic URLs will often go on forever and ever for example - the www has to break down
from main topic to sub topic to detailed topic to a set of images - and finally
the image itself).
To be sure, use the tiny black down arrow to reveal the true end of the line
(and with a magnifying glass if your text is as small as mine) - then just click the two little green curved arrows to restore.