odd / baffling navigation panel issue

Here's a challenge. A prize(*) to anyone who can explain this!

I've got a webite in XDP 6.0 with 6 pages using a Navigation Panel.

Having accidentally deleted the nav panel from page 4 I went to page 3, copied the panel, went back to page 4 and did a 'Paste in place' to put it back. I exported the site and navigation works 100%.

Here's the wierd part:

There are a total of 24 images making up the Nav buttons - 6 buttons each with 4 images for each state (mousedown,mouseup,mouseover and mousedownselect - I use Covoxer's tweak for the 'extra' states). These 24 images are reused across all pages except for page 4 where 13 of the images have been re-exported. The 'copies' are the same physical dimensions, look identical but are 1 or 2 bytes larger than their counterparts.

I am totally at a loss to explain this.

(*) No prize implied by this offer :D

Hi, worth uploading the file to allow for further investigation..

I suppose that MIGHT help... :o

The attached file has been stripped down to the bare minimum. 3 Pages, and a Nav Bar.

Page 1 and 2 will use the same images for the nav bar but page 3 will use different image files, but only for SOME of the button states (!?!?)

I've done some more experiments and it appears to be down to page 3 being a different size. If I make the page all the same then the extra images go away. However I am not able to replicate this problem on a separate test site created afresh, which leads me to think there is some kind of corruption within my .xar file.