[en] It is demonstrated how circularly polarized Moessbauer γ-rays may be used to obtain an unambiguous determination of the signs of two hyperfine fields which may exist together in a single sample. Such a situation is often encountered when, for unavoidable reasons, a probe nucleus is found to occupy two different sites. This is the case for the Heusler type alloy Co₂TiSn. The Moessbauer absorption spectrum using a ¹¹⁹Sn source shows that in addition to the magnetic spectrum attributed to Sn atoms occupying the expected X sites in the Heusler (A₂BX) structure, there is an additional magnetic component due to Sn atoms occupying some other site or phase. It is shown that both hyperfine fields are positive having values of 78.8 and 12.2 kG respectively