We investigate the impact of displaced heavyquark matching scales in a global fit. The heavy-quark matching scale mu m determines at which energy scale mu the QCD theory transitions from NF to NF + 1 in the variable flavor number scheme (VFNS) for the evolution of the parton distribution functions (PDFs) and strong coupling alpha(S)(mu). We study the variation of the matching scales, and their impact on a global PDF fit of the combinedHERAdata. As the choice of the matching scale mu m effectively is a choice of scheme, this represents a theoretical uncertainty; ideally, we would like to see minimal dependence on this parameter. For the transition across the charm quark (from N-F = 3 to 4), we find a large mu(m) = mu(c) dependence of the global fit chi(2) at NLO, but this is significantly reduced at NNLO. For the transition across the bottom quark (from NF = 4 to 5), we have a reduced mu(m) = mu(b) dependence of the chi(2) at both NLO and NNLO as compared to the charm. This feature is now implemented in xFitter 2.0.0, an open source QCD fit framework.