Andy wrote:

Are these real Duracells?

Without prejudice to any particular shop or chain, be careful of cheap
batteries and particularly of Duracell. There are many of these in
circulation that are the cheapest of zin chloride cells, with a fake
label and packaging. Some even have the original "lucky golden
hedgehog" wrapper on underneath. Rip one apart and check the inner
construction if you want to be sure.

Easily (in the shop) you can check the shape of the tin and whether
this is appropriate for an alkaline. Zinc carbon or zinc chloride cells
have the insulator at the +ve end (the nipple), alkalines have it at
the flat -ve end. I've not seen any myself yet, but there are also now
said to be fake alkalines masquerading as Duracells.

I doubt if this faking problem is limited to Duracells, they're just a
recognisable brand to forge.

Personally I don't like Duracells and find Ikea's own to be the best
performance and best price.