1991 HarperCollins Hardback Slipcase Lord of the Rings

I recently acquired a second copy of the 1991 HarperCollins Lord of the Rings Hardbacks with John Howe Covers in a red slipcase. This is the link to the item on Deagol's excellent site.

http://www.tolkienbooks.net/html/lotr-sc-hc_1.htm

I was suprised to notice that it was not the same size as my existing slipcase set and that there are at least two variants of this set.

One set is 11.2 cm (width of the slipcase) and is a light red colour.

My second set is 11.9 cm (width of the slipcase) and is a darker red colour.

I was also suprised to see that the books are not interchangeable as they are sized for the slipcases, so the books are also different widths. The books are not interchangeable as the slipcases are designed to fit the width of the books. It looks like the binder either fractionally increased or decreased the width of the books by a few millimeters during the binding process and so a second slipcase had to be made to accomodate. Internally they all show as first printings of this edition and are bound from the same sheets.

If anyone has one of these boxed sets, can you measure it as I am interested in finding out which width is the more common.

Andrew