There are in essence two reasons why we witness such a multitude of name variants in period sources:
The first has to do with a fact that most names were written as someone guessed how they should be written, since the modern spelling standards were not yet established then. Thus as long as it looked similar to how someone would pronounce the name, it was acceptable.
The second had to do with a geographic confluence of at least four cultures that were merging during the time of Viennese classicism: The Italian, Germanic, French and Slavic. Each of these has had its own syntax, so respectively the personal names from one would have been arranged to the syntax of the other, pending on the preferences of majority in particular area. Since the rules of transfer were not so strict, a number of variants came to be that we can witness today on all period manuscripts, letters and other official records.
Furthermore, since the Italian style was very fashionable in period Vienna, many musicians would Italianize their names on purpose in their musical presentations. The political events, such as Napoleon's conquests have also had an impact on many European regions and sometimes it was common to Francophonize names as well. There were nevertheless even instances where the original Italian names were Germanized, which can sometime make the matter of identification even more complicated.
This is why a need for a single Uniform Name has appeared, and more about it you can read at the Name Authority section.
Posted: September 30, 2010