I have version 1.6.5. I could email it to you. AFAIK that was the most recent version before the release of 2.0.
In general, you can get into trouble by doing automatic upgrades. You can have multiple versions of a plugin or theme on your server if you upload them via FTP. I wouldn’t attempt to activate them simultaneously, but you can switch back & forth. So, say you download a plugin, and the folder name is testplugin. Change the folder name to testpluginv1-6-5 before uploading. This indicates the version number in the folder name which is kind of handy. It also allows you to have more than one version of the plugin on your server. So, when you upgrade by uploading a folder called testpluginv1-6-6, deactivating the old one and activating the new one, you have a backup on your server and you can easily switch back or eventually delete the old plugin. The rules are pretty much the same for themes.
So, automatic upgrading of plugins & themes is convenient, but if you manually upgrade you don’t have to delete the previous version from the server, and don’t have to worry about making a backup.
HTH