Comparison of the retrieved IMF when adopting one slope vs. two slopes in the center of NGC3309 (upper panels) and NGC3311 (lower panels). Solid lines refer to a single-slope IMF while dashed lines to a double-slope IMF. The right panels show the mismatch parameter α _r obtained in both cases; dashed and dotted–dashed horizontal tan lines indicate the Kroupa and Salpeter values, respectively. The two IMF slopes are mutually degenerate when fitted together, causing X1 to hit unnaturally high values at the edge of model limits. To better highlight the uncertainties coming from the fit alone, in these plots error bars do not include systematic errors.