Duplicate render paths

For whatever reason i always get the messages/errors that no one on the internet has gotten ever (Or so it seems). I keep getting a message with "Duplicate render paths" and the description says "Please enter unique sub-folder names for each additional output in the render settings". Regardless of how i word it, i cannot find any articles related to this on google, nor youtube. I change the path to where the video is going, i change the name of the file and nothing works. It is with specific render settings that i am choosing, so as soon as i change the format from MKV to Quicktime, or something else, it works. I am not sure what i am doing wrong. Please help and sorry if there was another article about this already. I just couldnt find it.

I would refer to the user manual as all info regarding your issue is in the Deliver Page section.

MKV is not really a standardised wrapper, I'd resort to .MXF or .MOV. (or even MP4, although more limited).