They are included because each font was created to solve various problems. Woff and woff2 are the latest formats designed to stop font piracy. Svg is also a newer format, which is a vector file and is used on iOS mobile devices. Tff and eot are old school formats used by older browsers, but they allow anyone to download and use the font for free.
Short answer: all of them are included for compatibility with several versions.
See: Why should we include ttf, eot, woff, svg, ... in the font
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