Abstract We experimentally investigated the soliton collisions between soliton molecules and deuterogenic solitons spontaneously generated on the continuous wave (cw) noise background in an ultrafast erbium-doped fiber laser mode locked with MoS₂ saturable absorber (SA). The dynamics of the soliton collisions were observed using the time-stretch dispersion Fourier transform technique. The noise-induced deuterogenic solitons first undergo spectral broadening and wavelength shifting, then collide successively with a soliton molecule and eventually vanish. Within the simple collision framework, the spectral-temporal dynamics of soliton collision would help to unveil the self-stabilization mechanism of the soliton molecules in consideration of dispersive wave shedding. This nonlinear dynamics is similar to the soliton rain, except that complex condensed soliton phase is substituted with a soliton molecule.