Bell Bottom George

I wonder if some of you more technically minded persons out there would be able to answer this query ?

I have just bought the Laurel & Hardy 21-disc box set from HMV, at the sale price of £50 (bargain !). However, as I was getting one of the discs out of the case I just happened to notice that from the playing side I could see straight through the disc and make out the label on the other side ! I`ve looked at other discs in the set and they are all transparent..........They play absolutely fine, but should this be right ? None of my other Dvds are transparent at all.

Your thoughts please, especially someone who owns the same set.........

"What larks we had Mr Pip...........what larks !"