Not good, key terminals in two copies (including return)

I have two pieces successively sent back because some keys clamps.
We have long been a K120 - but in black - here in use that has always worked flawlessly,
so we wanted to buy a external laptop keyboard again a K120, and the price was very good here with less than 10.

Unfortunately, the batch is that I have caught here in November / December 2014 apparently not okay because the Enter key (and other) terminals extreme. No matter where and how you press Enter, nearly half of keystrokes is not recognized, and the two copies in a row.

Other key terminals as well.

Too bad, because I have to look good for another keyboard.