Posts being cannibalised by it's resyndicated version on Medium.c0m

Just wondering if anyone has thoughts.

I post to our blog, then often import content (with the canonical 'import') into Medium afterwards.

A few posts are being cannibalised in Google, ranking below (often not at all) where the medium article is in 1-5 positions.

Is that something I should worry about if traffic is still filtering through to our site, or just stop posting on medium altogether?

THanks in advance.