Kraken

I have had 3 SBE2S great guns. Passed down 2 to sons. Just bought grandson (age 8 months) a. 20 gauge M2 for me to take to South Dakota to “break-in” for him. I really like how it mounts and patterns. Only trouble is it randomly mis-feeds forcing me to get out my pocket knife to get things un jammed. After firing and ejecting spent shell, a new shell is released and flipped up to be grabbed by the bolt but somehow another shell is released out of the tube and gets lodged against the shell that is getting chambered. Has anyone ever had this problem? Any ideas of how to fix it?