Likely to make it simple for retailers to accept euro. Making it exactly two means the retailers would lose money on the exchange spread. Another example is with 1 hkd = 0.97 mop.
B/c the conversion to Euro happened later. It was already fixed after the hyper inflation in 1997.
The initital rate was 1000 levs = 1 DM, in 1999 there was a denomination of 1000 : 1, same year the Euro happened and the Deutsche mark enjoyed the same rate to the Euro.