  Magnetic skyrmions are vortex-like topological spin textures often observed
to form a triangular-lattice skyrmion crystal in structurally chiral magnets
with Dzyaloshinskii-Moriya interaction. Recently $\beta$-Mn structure-type
Co-Zn-Mn alloys were identified as a new class of chiral magnet to host such
skyrmion crystal phases, while $\beta$-Mn itself is known as hosting an
elemental geometrically frustrated spin liquid. Here we report the intermediate
composition system Co$_7$Zn$_7$Mn$_6$ to be a unique host of two disconnected,
thermal-equilibrium topological skyrmion phases; one is a conventional skyrmion
crystal phase stabilized by thermal fluctuations and restricted to exist just
below the magnetic transition temperature $T_\mathrm{c}$, and the other is a
novel three-dimensionally disordered skyrmion phase that is stable well below
$T_\mathrm{c}$. The stability of this new disordered skyrmion phase is due to a
cooperative interplay between the chiral magnetism with Dzyaloshinskii-Moriya
interaction and the frustrated magnetism inherent to $\beta$-Mn.
