Previous/Next odd sequencing issue

I have a site that sells autographs so some product names are the same for example I have 4 Bill Nighy signatures. In a list of Actors the Previous/Next function lists these as 21, 22, 23 and 24 respectively.

BUT in the alphabetical list, clicking on the first Bill Nighy, I would expect Previous/Next to show 21 but it is 23 so consequently when I click next I move to Bill Nighy 24 then another next click gives me the next name in the list - I don't get to see the other 2 Bill Nighy that I know are there because they appear in the alphabetical list.

Something has gone real screwy with the numbering but I can't see what. I've tried altering the Product Info sort order etc but to no avail - the sequencing still sucks.

Any help on this would be greatly appreciated.

The url for the site is:

http://www.movieautographsww.com and the category example is Actors.

Thanks.

There are a number of listings ...

The Product _info page Prev/Next is controlled by the setting in the Configuration ... Product Info ...

The numbers have little consequence to the Product as you will add and delete Products in various orders ...

If sorted by Product Name, then the Products will appear in order by Product Name as they are grabbed in the SELECT statement in that order ...

Thanks. That doesn't fix it though - I have Product Info sort order set to Product Name but still have the problem - is there something else I should be looking for?

What is the Product Listing Sort Order based on?

What is the Product Info Sort Order based on?