  We compare double-differential normalized production cross sections for
top-antitop $+ X$ hadroproduction at NNLO QCD accuracy, as obtained through a
customized version of the MATRIX framework interfaced to PineAPPL, with recent
data by the ATLAS and CMS collaborations. We take into account theory
uncertainties due to scale variation and we see how predictions vary as a
function of parton distribution function (PDF) choice and top-quark pole mass
value, considering different state-of-the-art PDF fits with their
uncertainties. Notwithstanding the overall reasonable good agreement, we
observe discrepancies at the level of a few $\sigma$'s between data and
theoretical predictions in some kinematical regions, which can be alleviated by
refitting the top-quark mass value, and/or the PDFs and/or $\alpha_s(M_Z)$,
considering the correlations between these three quantities. In a fit of
top-quark mass standalone, we notice that, for all considered PDF +
$\alpha_s(M_Z)$ sets used as input, some datasets point towards top-quark pole
mass values lower by about $2\,\sigma$'s than those emerging from fitting other
datasets, suggesting a possible tension between experimental measurements using
different decay channels, and/or the need of better estimating uncertainties on
the latter.
