i dont know why s this happening but when i use level sequencer the charcter get duplicated only when sequencer playing as you can see my world settings already set to none why s second charcter spawning
I have the exact same problem! I have been trying to solve this for hours!! Tell me if you find a solution, I will tell you if I find one 
I found a solution for my problem but It doesn’t seem to work with your case, since my solution was erasing a Shot Tack in my master Sequence that was kind of duplicating everything. but someone answer my post with a solution tahnt could work for your case.