I went into the minecraft launcher, clicked 'launch options', clicked 'add new', set a name and chose minecraft version old_alpha inf-20100618, as I wanted to play throughout the old minecraft versions. Except, when I started it up, minecraft crashed every time, no matter what I changed. It did this with all the other old versions as well...
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Most probably this is caused, because you didn't create a separate directory for the old version.
See MCL-5837.