not an expert on the amd side but google suggests the 6800xt is better than a 2060super. both those frame counts look kinda low though getting 60 is doable even on 10 series gpus.

similar pcs is kinda vague though. are they running similar displays at similar resolutions? maybe hes on a 1080 panel while your on 1440? are you playing at similar settings? are you on max while hes only on high for example?

endless variables?

if they are similar builds swap the gpus over for a day or 3 and see what happens?