The dispute between Greece and Macedonia over who gets to keep the name "Macedonia" has been ongoing for 20 years now. Is this a unique dispute or have there been any other similar disputes in recent history?
No, i don't know if this counts as recent but there was a dispute between the UK and the Irish on if Ireland should be named Eire or Ireland, and as the UK says, "His Majesty's Government in the United Kingdom has considered the position created by the new Constitution ... of the Irish Free State, in future to be described under the Constitution as 'Eire' or 'Ireland' ... [and] cannot recognise that the adoption of the name 'Eire' or 'Ireland', or any other provision..." quote from: https://en.wikipedia.org/wiki/Names_of_the_Irish_state#Name_dispute_with_the_UK
Anyhow the UK won this argument and now it is called "Ireland".
Similar but different: The United States of Mexico have occasionally expressed some concern about some other country that's sometimes called "the united states".
In contrast to the Macedonian case, it seems to be mostly an internal and unilateral debate, as opposed to trying to convince some other nation to change.