Bulgaria / Greece : Double Standard?

The European Union and Bulgaria are arguing about how to spell the word euro.
The problem lies with Bulgaria’s Cyrillic alphabet (the third alphabet in EU, after the Latin and the Greek ones), under which the common European currency is spelt “evro” rather than euro.
This discussion threatens to block the signing of an EU accord with Balkan state Montenegro. Bulgarian diplomats said they could only sign the document if euro is spelt correctly in the Bulgarian version of the agreement:

“This is part of our national identity. We brought the third alphabet into the European Union and it’s a matter of respect for linguistic diversity,”

Bulgaria is presently the only EU member to widely use the Cyrillic alphabet but it is also used in Balkan countries that are lining up to join the EU.
Other countries where the euro is pronounced differently, including Slovenia, have tried to obtain a different spelling of the common currency, but they have failed. Except for Greece.

Unlike Slovenia which uses the Latin alphabet, Greece had put forward its different alphabet as an argument - something that Bulgarians are trying to do as well.

The European Central Bank insists that the name of the common currency must be the same in all the official languages of the EU. On the other hand, the existence of different alphabets should be taken into account - opinion also supported by Multilingualism Commissioner, Leonad Orban.

Of course, for some it looks like a minor and ridiculous matter, but Bulgaria brings the same arguments as Greece. Why “yes” for Greece and “no” for Bulgaria?