We have just returned from a cruise of the eastern Med which of course takes in a lot of European countries so we took quite a lot of Euros with us, when we reached Corfu we were getting a bit light on Euros so got some out of the hole in the wall at the cruise terminal, I have just today looked at the euros that are left and noticed that the Greek 10 Euro note is different from the rest, it seems to be much darker in colour that the rest is this normal? (before anybody says they are fake, the shops in Corfu town took them OK)
I think you will find they are just an older version, several of the euro notes were updated in the last year or so (precise details unknown) and both types are in circulation across europe so no need to worry IMO.