5 pence 2008 type Dent - orientation coin alignment

Hi,
I went in England few weeks ago and I  kept 3 coins of 5 pence (this coin)
https://en.numista.com/catalogue/pieces6612.html
2 coins of 2008
1 coin of 2010
My coin of 2010 and one coin of 2008 are in medal coin orientation
and the other coin of 2008 are in alignment coin orientation



It's possible ? It's normal ?

I have heard of them. It is (to me) a known error. I think 2008 was a bad year for the Royal Mint as that was also when they made the 'mule' undated 20 pence coin. I have that 20p but not the 5p, so it gives me inspiration that they can still be found in change!
 They have sold for over £50 before, and the one below is asking £70
http://www.ebay.co.uk/itm/5p-coin-error-180-degree-turn-RARE-/260878226152?pt=UK_Coins_BritishDecimal_RL&hash=item3cbd8dd2e8

I added a line for this error. maybe this becomes a common variety known in catalogs.

Thanks for yours answers. I had this coin in circulation, so I think it's possible to found one, but I hope that you are lucky  
Thank you Makake for line.