Upgraded our testenvironment to 3.9.3, and started seeing duplicate events on a catchup subscription. Same stream and seqnumber, but with different eventposition. Downgrading to 3.8.0 solved it, but it still reads the previous events out as duplicates. Looking at the streams in the ui looks right.
Updated the client the .net client lib to 3.9.4 in case of incompatiblity, but no difference.
Could not reproduce locally either, so only seen it on one machine.