You can find info about it on Hidden Palace. However link redirects to new page.
https://hiddenpalace.org/Crash_Bandicoot_2:_Cortex_Strikes_Back_(Aug_9,_1997_prototype)
Lucky enough page is archived.
https://web.archive.org/web/20190115005230/https://hiddenpalace.org/Crash_Bandicoot_2:_Cortex_Strikes_Back_(Aug_9,_1997_prototype)
You can also download image of this verion from there.
https://web.archive.org/web/20190115005230/https://hiddenpalace.org/w/images/9/90/Crash_Bandicoot_2_-_Cortex_Strikes_Back_(Aug_9%2C_1997_prototype).rar
I'm curious if this beta is real and why the removed mentions about it.