In Mixpanel Funnels, the "Time to Convert" (which would include metrics like median and average time to resolve/convert) uses the Totals counting method, not Uniques. This means the calculation is based on all funnel conversion attempts, not just the first attempt per user. You can select aggregations such as average, median, percentiles, min, and max for "Time to Convert" when using Totals. This is explicitly stated in the documentation:
So, both median and average "time to resolve" in funnels are calculated using the Totals counting method.